diff --git a/configs/_base_/datasets/coco.yml b/configs/_base_/datasets/coco.yml
index 6f8af073925f10f94c64cad83b7876f17553a226..628c8ddf37d8a5798c1db151c1476b68a4cc0e2e 100644
--- a/configs/_base_/datasets/coco.yml
+++ b/configs/_base_/datasets/coco.yml
@@ -6,6 +6,7 @@ TrainDataset:
     image_dir: train2017
     anno_path: annotations/instances_train2017.json
     dataset_dir: dataset/coco
+    mixup_epoch: 250
 
 EvalDataset:
   !COCODataSet
diff --git a/configs/_base_/models/yolov3_darknet53.yml b/configs/_base_/models/yolov3_darknet53.yml
index 376bb618b6bf65c230bbfe36767b4246e3267ad3..6e4bc216ad6376ec3d0b51cdcb344c49fde41d88 100644
--- a/configs/_base_/models/yolov3_darknet53.yml
+++ b/configs/_base_/models/yolov3_darknet53.yml
@@ -13,18 +13,21 @@ YOLOv3:
 DarkNet:
   depth: 53
   return_idx: [2, 3, 4]
+  norm_type: sync_bn
 
 YOLOv3FPN:
   feat_channels: [1024, 768, 384]
 
 YOLOv3Head:
-  anchors: [10, 13, 16, 30, 33, 23, 30, 61, 62, 45, 59, 119, 116, 90, 156, 198, 373, 326]
+  anchors: [[10, 13], [16, 30], [33, 23],
+            [30, 61], [62, 45], [59, 119],
+            [116, 90], [156, 198], [373, 326]]
   anchor_masks: [[6, 7, 8], [3, 4, 5], [0, 1, 2]]
   loss: YOLOv3Loss
 
 YOLOv3Loss:
   ignore_thresh: 0.7
-  downsample: 32
+  downsample: [32, 16, 8]
   label_smooth: true
 
 BBoxPostProcess:
diff --git a/configs/_base_/readers/yolov3_reader.yml b/configs/_base_/readers/yolov3_reader.yml
index b6d4c93cbc92d69e323bd101f56f20a7f1611246..32994714e4687209c0019db0a546c16228a78878 100644
--- a/configs/_base_/readers/yolov3_reader.yml
+++ b/configs/_base_/readers/yolov3_reader.yml
@@ -1,26 +1,23 @@
 worker_num: 2
 TrainReader:
   inputs_def:
-    fields: ['image', 'gt_bbox', 'gt_class', 'gt_score']
+    fields: ['image', 'gt_bbox', 'gt_class', 'gt_score', 'im_shape', 'scale_factor']
     num_max_boxes: 50
   sample_transforms:
-    - DecodeImage: {to_rgb: True, with_mixup: True}
-    - MixupImage: {alpha: 1.5, beta: 1.5}
-    - ColorDistort: {}
-    - RandomExpand: {fill_value: [123.675, 116.28, 103.53]}
-    - RandomCrop: {}
-    - RandomFlipImage: {is_normalized: false}
-    - NormalizeBox: {}
-    - PadBox: {num_max_boxes: 50}
-    - BboxXYXY2XYWH: {}
+    - DecodeOp: {}
+    - MixupOp: {alpha: 1.5, beta: 1.5}
+    - RandomDistortOp: {}
+    - RandomExpandOp: {fill_value: [123.675, 116.28, 103.53]}
+    - RandomCropOp: {}
+    - RandomFlipOp: {}
   batch_transforms:
-  - RandomShape: {sizes: [320, 352, 384, 416, 448, 480, 512, 544, 576, 608], random_inter: True}
-  - NormalizeImage: {mean: [0.485, 0.456, 0.406], std: [0.229, 0.224, 0.225], is_scale: True, is_channel_first: false}
-  - Permute: {to_bgr: false, channel_first: True}
-  # Gt2YoloTarget is only used when use_fine_grained_loss set as true,
-  # this operator will be deleted automatically if use_fine_grained_loss
-  # is set as false
-  - Gt2YoloTarget: {anchor_masks: [[6, 7, 8], [3, 4, 5], [0, 1, 2]], anchors: [[10, 13], [16, 30], [33, 23], [30, 61], [62, 45], [59, 119], [116, 90], [156, 198], [373, 326]], downsample_ratios: [32, 16, 8]}
+    - BatchRandomResizeOp: {target_size: [320, 352, 384, 416, 448, 480, 512, 544, 576, 608], random_size: True, random_interp: True, keep_ratio: False}
+    - NormalizeBoxOp: {}
+    - PadBoxOp: {num_max_boxes: 50}
+    - BboxXYXY2XYWHOp: {}
+    - NormalizeImageOp: {mean: [0.485, 0.456, 0.406], std: [0.229, 0.224, 0.225], is_scale: True}
+    - PermuteOp: {}
+    - Gt2YoloTargetOp: {anchor_masks: [[6, 7, 8], [3, 4, 5], [0, 1, 2]], anchors: [[10, 13], [16, 30], [33, 23], [30, 61], [62, 45], [59, 119], [116, 90], [156, 198], [373, 326]], downsample_ratios: [32, 16, 8]}
   batch_size: 8
   shuffle: true
   drop_last: true
@@ -28,24 +25,24 @@ TrainReader:
 
 EvalReader:
   inputs_def:
-    fields: ['image', 'im_size', 'im_id']
+    fields: ['image', 'im_shape', 'scale_factor', 'im_id']
     num_max_boxes: 50
   sample_transforms:
-    - DecodeImage: {to_rgb: True}
-    - ResizeImage: {target_size: 608, interp: 2}
-    - NormalizeImage: {mean: [0.485, 0.456, 0.406], std: [0.229, 0.224, 0.225], is_scale: True, is_channel_first: false}
-    - PadBox: {num_max_boxes: 50}
-    - Permute: {to_bgr: false, channel_first: True}
+    - DecodeOp: {}
+    - ResizeOp: {target_size: [608, 608], keep_ratio: False, interp: 2}
+    - NormalizeImageOp: {mean: [0.485, 0.456, 0.406], std: [0.229, 0.224, 0.225], is_scale: True}
+    - PadBoxOp: {num_max_boxes: 50}
+    - PermuteOp: {}
   batch_size: 1
   drop_empty: false
 
 TestReader:
   inputs_def:
     image_shape: [3, 608, 608]
-    fields: ['image', 'im_size', 'im_id']
+    fields: ['image', 'im_shape', 'scale_factor', 'im_id']
   sample_transforms:
-    - DecodeImage: {to_rgb: True}
-    - ResizeImage: {target_size: 608, interp: 2}
-    - NormalizeImage: {mean: [0.485, 0.456, 0.406], std: [0.229, 0.224, 0.225], is_scale: True, is_channel_first: false}
-    - Permute: {to_bgr: false, channel_first: True}
+    - DecodeOp: {}
+    - ResizeOp: {target_size: [608, 608], interp: 2}
+    - NormalizeImageOp: {mean: [0.485, 0.456, 0.406], std: [0.229, 0.224, 0.225], is_scale: True}
+    - PermuteOp: {}
   batch_size: 1
diff --git a/ppdet/data/reader.py b/ppdet/data/reader.py
index c279e5abd9b70119d5b898f0ba4614d369412691..2533217d6aa91bfb272754d170ef323e38f59951 100644
--- a/ppdet/data/reader.py
+++ b/ppdet/data/reader.py
@@ -11,17 +11,18 @@ import numpy as np
 from paddle.io import DataLoader
 from ppdet.core.workspace import register, serializable, create
 from .sampler import DistributedBatchSampler
-from .transform import operators
-from .transform import batch_operators
+from . import transform
+from .transform import operator, batch_operator
 
 logger = logging.getLogger(__name__)
 
 
 class Compose(object):
-    def __init__(self, transforms, fields=None, from_=operators,
+    def __init__(self, transforms, fields=None, from_=transform,
                  num_classes=81):
         self.transforms = transforms
         self.transforms_cls = []
+        output_fields = None
         for t in self.transforms:
             for k, v in t.items():
                 op_cls = getattr(from_, k)
@@ -29,7 +30,17 @@ class Compose(object):
                 if hasattr(op_cls, 'num_classes'):
                     op_cls.num_classes = num_classes
 
+                if op_cls in [
+                        transform.Gt2YoloTargetOp, transform.Gt2YoloTarget
+                ]:
+                    output_fields = ['image', 'gt_bbox']
+                    output_fields.extend([
+                        'target{}'.format(i)
+                        for i in range(len(v['anchor_masks']))
+                    ])
+
         self.fields = fields
+        self.output_fields = output_fields if output_fields else fields
 
     def __call__(self, data):
         if self.fields is not None:
@@ -47,11 +58,11 @@ class Compose(object):
                             format(f, e, str(stack_info)))
                 raise e
 
-        if self.fields is not None:
+        if self.output_fields is not None:
             data_new = []
             for item in data:
                 batch = []
-                for k in self.fields:
+                for k in self.output_fields:
                     batch.append(item[k])
                 data_new.append(batch)
             batch_size = len(data_new)
@@ -80,8 +91,7 @@ class BaseDataLoader(object):
                  num_classes=81,
                  with_background=True):
         # out fields 
-        self._fields = copy.deepcopy(inputs_def[
-            'fields']) if inputs_def else None
+        self._fields = inputs_def['fields'] if inputs_def else None
         # sample transform
         self._sample_transforms = Compose(
             sample_transforms, num_classes=num_classes)
@@ -89,8 +99,9 @@ class BaseDataLoader(object):
         # batch transfrom 
         self._batch_transforms = None
         if batch_transforms:
-            self._batch_transforms = Compose(batch_transforms, self._fields,
-                                             batch_operators, num_classes)
+            self._batch_transforms = Compose(batch_transforms,
+                                             copy.deepcopy(self._fields),
+                                             transform, num_classes)
 
         self.batch_size = batch_size
         self.shuffle = shuffle
@@ -100,19 +111,24 @@ class BaseDataLoader(object):
     def __call__(self,
                  dataset,
                  worker_num,
-                 device,
+                 device=None,
+                 batch_sampler=None,
                  return_list=False,
                  use_prefetch=True):
         self._dataset = dataset
         self._dataset.parse_dataset(self.with_background)
         # get data
-        self._dataset.set_out(self._sample_transforms, self._fields)
+        self._dataset.set_out(self._sample_transforms,
+                              copy.deepcopy(self._fields))
         # batch sampler
-        self._batch_sampler = DistributedBatchSampler(
-            self._dataset,
-            batch_size=self.batch_size,
-            shuffle=self.shuffle,
-            drop_last=self.drop_last)
+        if batch_sampler is None:
+            self._batch_sampler = DistributedBatchSampler(
+                self._dataset,
+                batch_size=self.batch_size,
+                shuffle=self.shuffle,
+                drop_last=self.drop_last)
+        else:
+            self._batch_sampler = batch_sampler
 
         loader = DataLoader(
             dataset=self._dataset,
@@ -152,7 +168,7 @@ class EvalReader(BaseDataLoader):
                  batch_transforms=None,
                  batch_size=1,
                  shuffle=False,
-                 drop_last=False,
+                 drop_last=True,
                  drop_empty=True,
                  num_classes=81,
                  with_background=True):
diff --git a/ppdet/data/source/coco.py b/ppdet/data/source/coco.py
index 69e383ac795671ce700b39672b157d8dbe8098f8..d92eef9b2727b44be41e093ce87a85b13812306b 100644
--- a/ppdet/data/source/coco.py
+++ b/ppdet/data/source/coco.py
@@ -28,9 +28,18 @@ class COCODataSet(DetDataset):
                  dataset_dir=None,
                  image_dir=None,
                  anno_path=None,
+                 mixup_epoch=-1,
+                 cutmix_epoch=-1,
+                 mosaic_epoch=-1,
                  sample_num=-1):
-        super(COCODataSet, self).__init__(dataset_dir, image_dir, anno_path,
-                                          sample_num)
+        super(COCODataSet, self).__init__(
+            dataset_dir,
+            image_dir,
+            anno_path,
+            sample_num,
+            mixup_epoch=mixup_epoch,
+            cutmix_epoch=cutmix_epoch,
+            mosaic_epoch=mosaic_epoch)
         self.load_image_only = False
         self.load_semantic = False
 
diff --git a/ppdet/data/source/dataset.py b/ppdet/data/source/dataset.py
index f5ef1aad5f0982b7d5b1fbe623d3fe608a08e01c..2b3136dc56a6428af7fd8ae9ac62e3d2969fc461 100644
--- a/ppdet/data/source/dataset.py
+++ b/ppdet/data/source/dataset.py
@@ -33,6 +33,9 @@ class DetDataset(Dataset):
                  anno_path=None,
                  sample_num=-1,
                  use_default_label=None,
+                 mixup_epoch=-1,
+                 cutmix_epoch=-1,
+                 mosaic_epoch=-1,
                  **kwargs):
         super(DetDataset, self).__init__()
         self.dataset_dir = dataset_dir if dataset_dir is not None else ''
@@ -40,6 +43,10 @@ class DetDataset(Dataset):
         self.image_dir = image_dir if image_dir is not None else ''
         self.sample_num = sample_num
         self.use_default_label = use_default_label
+        self.epoch = 0
+        self.mixup_epoch = mixup_epoch
+        self.cutmix_epoch = cutmix_epoch
+        self.mosaic_epoch = mosaic_epoch
 
     def __len__(self, ):
         return len(self.roidbs)
@@ -47,6 +54,21 @@ class DetDataset(Dataset):
     def __getitem__(self, idx):
         # data batch
         roidb = copy.deepcopy(self.roidbs[idx])
+        if self.mixup_epoch == 0 or self.epoch < self.mixup_epoch:
+            n = len(self.roidbs)
+            idx = np.random.randint(n)
+            roidb = [roidb, copy.deepcopy(self.roidbs[idx])]
+        elif self.cutmix_epoch == 0 or self.epoch < self.cutmix_epoch:
+            n = len(self.roidbs)
+            idx = np.random.randint(n)
+            roidb = [roidb, copy.deepcopy(self.roidbs[idx])]
+        elif self.mosaic_epoch == 0 or self.epoch < self.mosaic_epoch:
+            n = len(self.roidbs)
+            roidb = [roidb, ] + [
+                copy.deepcopy(self.roidbs[np.random.randint(n)])
+                for _ in range(3)
+            ]
+
         # data augment
         roidb = self.transform(roidb)
         # data item 
diff --git a/ppdet/data/transform/__init__.py b/ppdet/data/transform/__init__.py
index 8c606b3aacdeed91559c39471ac92d67874313eb..f2496426f493148c108a3b34bb43d7689da5f01a 100644
--- a/ppdet/data/transform/__init__.py
+++ b/ppdet/data/transform/__init__.py
@@ -14,6 +14,8 @@
 
 from . import operators
 from . import batch_operators
+from . import operator
+from . import batch_operator
 
 # TODO: operators and batch_operators will be replaced by operator and batch_operator
 from .operators import *
diff --git a/ppdet/data/transform/batch_operator.py b/ppdet/data/transform/batch_operator.py
index e02a7d6e4082635ea071f8c2b3ee239a1229910e..870f1ad3b052abf6937f509476010f1c38580909 100644
--- a/ppdet/data/transform/batch_operator.py
+++ b/ppdet/data/transform/batch_operator.py
@@ -156,7 +156,7 @@ class BatchRandomResizeOp(BaseOperator):
     def __init__(self,
                  target_size,
                  keep_ratio=True,
-                 interp=cv2.INTER_LINEAR,
+                 interp=cv2.INTER_NEAREST,
                  random_size=True,
                  random_interp=False):
         super(BatchRandomResizeOp, self).__init__()
diff --git a/ppdet/data/transform/operator.py b/ppdet/data/transform/operator.py
index 76d399be0a2d10837f7cfaed7b10fdcda754667b..760383e91387f419d50ee1b433003745b8efcca0 100644
--- a/ppdet/data/transform/operator.py
+++ b/ppdet/data/transform/operator.py
@@ -25,7 +25,7 @@ try:
 except Exception:
     from collections import Sequence
 
-from numbers import Number
+from numbers import Number, Integral
 
 import uuid
 import logging
@@ -33,6 +33,7 @@ import random
 import math
 import numpy as np
 import os
+import copy
 
 import cv2
 from PIL import Image, ImageEnhance, ImageDraw
@@ -95,8 +96,8 @@ class BaseOperator(object):
         if isinstance(sample, Sequence):
             for i in range(len(sample)):
                 sample[i] = self.apply(sample[i], context)
-
-        sample = self.apply(sample, context)
+        else:
+            sample = self.apply(sample, context)
         return sample
 
     def __str__(self):
@@ -140,8 +141,8 @@ class DecodeOp(BaseOperator):
                 "image width.".format(im.shape[1], sample['w']))
             sample['w'] = im.shape[1]
 
-        sample['im_shape'] = im.shape[:2]
-        sample['scale_factor'] = [1., 1.]
+        sample['im_shape'] = np.array(im.shape[:2], dtype=np.int32)
+        sample['scale_factor'] = np.array([1., 1.], dtype=np.float32)
         return sample
 
 
@@ -182,6 +183,56 @@ class LightingOp(BaseOperator):
         return sample
 
 
+@register_op
+class RandomErasingImageOp(BaseOperator):
+    def __init__(self, prob=0.5, lower=0.02, higher=0.4, aspect_ratio=0.3):
+        """
+        Random Erasing Data Augmentation, see https://arxiv.org/abs/1708.04896
+        Args:
+            prob (float): probability to carry out random erasing
+            lower (float): lower limit of the erasing area ratio
+            heigher (float): upper limit of the erasing area ratio
+            aspect_ratio (float): aspect ratio of the erasing region
+        """
+        super(RandomErasingImageOp, self).__init__()
+        self.prob = prob
+        self.lower = lower
+        self.heigher = heigher
+        self.aspect_ratio = aspect_ratio
+
+    def apply(self, sample):
+        gt_bbox = sample['gt_bbox']
+        im = sample['image']
+        if not isinstance(im, np.ndarray):
+            raise TypeError("{}: image is not a numpy array.".format(self))
+        if len(im.shape) != 3:
+            raise ImageError("{}: image is not 3-dimensional.".format(self))
+
+        for idx in range(gt_bbox.shape[0]):
+            if self.prob <= np.random.rand():
+                continue
+
+            x1, y1, x2, y2 = gt_bbox[idx, :]
+            w_bbox = x2 - x1 + 1
+            h_bbox = y2 - y1 + 1
+            area = w_bbox * h_bbox
+
+            target_area = random.uniform(self.lower, self.higher) * area
+            aspect_ratio = random.uniform(self.aspect_ratio,
+                                          1 / self.aspect_ratio)
+
+            h = int(round(math.sqrt(target_area * aspect_ratio)))
+            w = int(round(math.sqrt(target_area / aspect_ratio)))
+
+            if w < w_bbox and h < h_bbox:
+                off_y1 = random.randint(0, int(h_bbox - h))
+                off_x1 = random.randint(0, int(w_bbox - w))
+                im[int(y1 + off_y1):int(y1 + off_y1 + h), int(x1 + off_x1):int(
+                    x1 + off_x1 + w), :] = 0
+        sample['image'] = im
+        return sample
+
+
 @register_op
 class NormalizeImageOp(BaseOperator):
     def __init__(self, mean=[0.485, 0.456, 0.406], std=[1, 1, 1],
@@ -350,7 +401,7 @@ class RandomDistortOp(BaseOperator):
                 lambda img: cv2.cvtColor(self.apply_saturation(cv2.cvtColor(img, cv2.COLOR_RGB2HSV)), cv2.COLOR_HSV2RGB),
                 lambda img: cv2.cvtColor(self.apply_hue(cv2.cvtColor(img, cv2.COLOR_RGB2HSV)), cv2.COLOR_HSV2RGB),
             ]
-            distortions = np.random.permutation(functions)[:count]
+            distortions = np.random.permutation(functions)[:self.count]
             for func in distortions:
                 img = func(img)
             sample['image'] = img
@@ -527,11 +578,11 @@ class ResizeOp(BaseOperator):
         super(ResizeOp, self).__init__()
         self.keep_ratio = keep_ratio
         self.interp = interp
-        if not isinstance(target_size, (int, list, tuple)):
+        if not isinstance(target_size, (Integral, Sequence)):
             raise TypeError(
                 "Type of target_size is invalid. Must be Integer or List or Tuple, now is {}".
                 format(type(target_size)))
-        if isinstance(target_size, int):
+        if isinstance(target_size, Integral):
             target_size = [target_size, target_size]
         self.target_size = target_size
 
@@ -627,11 +678,15 @@ class ResizeOp(BaseOperator):
 
         im = self.apply_image(sample['image'], [im_scale_x, im_scale_y])
         sample['image'] = im
-        sample['im_shape'] = [resize_h, resize_w]
-        scale_factor = sample['scale_factor']
-        sample['scale_factor'] = [
-            scale_factor[0] * im_scale_y, scale_factor[1] * im_scale_x
-        ]
+        sample['im_shape'] = np.array([resize_h, resize_w], dtype=np.int32)
+        if 'scale_factor' in sample:
+            scale_factor = sample['scale_factor']
+            sample['scale_factor'] = np.array(
+                [scale_factor[0] * im_scale_y, scale_factor[1] * im_scale_x],
+                dtype=np.float32)
+        else:
+            sample['scale_factor'] = np.array(
+                [im_scale_y, im_scale_x], dtype=np.float32)
 
         # apply bbox
         if 'gt_bbox' in sample and len(sample['gt_bbox']) > 0:
@@ -641,7 +696,7 @@ class ResizeOp(BaseOperator):
 
         # apply polygon
         if 'gt_poly' in sample and len(sample['gt_poly']) > 0:
-            sample['gt_poly'] = self.apply_segm(sample['gt_poly'], im_shape,
+            sample['gt_poly'] = self.apply_segm(sample['gt_poly'], im_shape[:2],
                                                 [im_scale_x, im_scale_y])
 
         # apply semantic
@@ -694,16 +749,16 @@ class MultiscaleTestResizeOp(BaseOperator):
         self.interp = interp
         self.use_flip = use_flip
 
-        if not isinstance(target_size, list):
+        if not isinstance(target_size, Sequence):
             raise TypeError(
-                "Type of target_size is invalid. Must be List, now is {}".
+                "Type of target_size is invalid. Must be List or Tuple, now is {}".
                 format(type(target_size)))
         self.target_size = target_size
 
-        if not isinstance(origin_target_size, list):
+        if not isinstance(origin_target_size, Sequence):
             raise TypeError(
-                "Type of target_size is invalid. Must be List, now is {}".
-                format(type(target_size)))
+                "Type of origin_target_size is invalid. Must be List or Tuple, now is {}".
+                format(type(origin_target_size)))
 
         self.origin_target_size = origin_target_size
 
@@ -753,10 +808,10 @@ class RandomResizeOp(BaseOperator):
             cv2.INTER_LANCZOS4,
         ]
         assert isinstance(target_size, (
-            int, Sequence)), "target_size must be int, list or tuple"
-        if random_size and not isinstance(target_size, list):
+            Integral, Sequence)), "target_size must be Integer, List or Tuple"
+        if random_size and not isinstance(target_size, Sequence):
             raise TypeError(
-                "Type of target_size is invalid when random_size is True. Must be List, now is {}".
+                "Type of target_size is invalid when random_size is True. Must be List or Tuple, now is {}".
                 format(type(target_size)))
         self.target_size = target_size
         self.random_size = random_size
@@ -816,7 +871,10 @@ class RandomExpandOp(BaseOperator):
         x = np.random.randint(0, w - width)
         offsets, size = [x, y], [h, w]
 
-        pad = Pad(size, pad_mode=-1, offsets=offsets)
+        pad = Pad(size,
+                  pad_mode=-1,
+                  offsets=offsets,
+                  fill_value=self.fill_value)
 
         return pad(sample, context=context)
 
@@ -1350,11 +1408,11 @@ class RandomScaledCropOp(BaseOperator):
         canvas[:min(dim, resize_h), :min(dim, resize_w), :] = img[
             offset_y:offset_y + dim, offset_x:offset_x + dim, :]
         sample['image'] = canvas
-        sample['im_shape'] = [resize_h, resize_w]
+        sample['im_shape'] = np.array([resize_h, resize_w], dtype=np.int32)
         scale_factor = sample['sacle_factor']
-        sample['scale_factor'] = [
-            scale_factor[0] * scale, scale_factor[1] * scale
-        ]
+        sample['scale_factor'] = np.array(
+            [scale_factor[0] * scale, scale_factor[1] * scale],
+            dtype=np.float32)
 
         if 'gt_bbox' in sample and len(sample['gt_bbox']) > 0:
             scale_array = np.array([scale, scale] * 2, dtype=np.float32)
@@ -1487,30 +1545,32 @@ class MixupOp(BaseOperator):
         if factor <= 0.0:
             return sample[1]
         im = self.apply_image(sample[0]['image'], sample[1]['image'], factor)
+        result = copy.deepcopy(sample[0])
+        result['image'] = im
         # apply bbox and score
-        gt_bbox1 = sample[0]['gt_bbox']
-        gt_bbox2 = sample[1]['gt_bbox']
-        gt_bbox = np.concatenate((gt_bbox1, gt_bbox2), axis=0)
-        gt_class1 = sample[0]['gt_class']
-        gt_class2 = sample[1]['gt_class']
-        gt_class = np.concatenate((gt_class1, gt_class2), axis=0)
-
-        gt_score1 = sample[0]['gt_score']
-        gt_score2 = sample[1]['gt_score']
-        gt_score = np.concatenate(
-            (gt_score1 * factor, gt_score2 * (1. - factor)), axis=0)
-
-        is_crowd1 = sample[0]['is_crowd']
-        is_crowd2 = sample[1]['is_crowd']
-        is_crowd = np.concatenate((is_crowd1, is_crowd2), axis=0)
-
-        sample = sample[0]
-        sample['image'] = im
-        sample['gt_bbox'] = gt_bbox
-        sample['gt_score'] = gt_score
-        sample['gt_class'] = gt_class
-        sample['is_crowd'] = is_crowd
-        return sample
+        if 'gt_bbox' in sample[0]:
+            gt_bbox1 = sample[0]['gt_bbox']
+            gt_bbox2 = sample[1]['gt_bbox']
+            gt_bbox = np.concatenate((gt_bbox1, gt_bbox2), axis=0)
+            result['gt_bbox'] = gt_bbox
+        if 'gt_class' in sample[0]:
+            gt_class1 = sample[0]['gt_class']
+            gt_class2 = sample[1]['gt_class']
+            gt_class = np.concatenate((gt_class1, gt_class2), axis=0)
+            result['gt_class'] = gt_class
+        if 'gt_score' in sample[0]:
+            gt_score1 = sample[0]['gt_score']
+            gt_score2 = sample[1]['gt_score']
+            gt_score = np.concatenate(
+                (gt_score1 * factor, gt_score2 * (1. - factor)), axis=0)
+            result['gt_score'] = gt_score
+        if 'is_crowd' in sample[0]:
+            is_crowd1 = sample[0]['is_crowd']
+            is_crowd2 = sample[1]['is_crowd']
+            is_crowd = np.concatenate((is_crowd1, is_crowd2), axis=0)
+            result['is_crowd'] = is_crowd
+
+        return result
 
 
 @register_op
@@ -1578,26 +1638,26 @@ class PadBoxOp(BaseOperator):
         bbox = sample['gt_bbox']
         gt_num = min(self.num_max_boxes, len(bbox))
         num_max = self.num_max_boxes
-        fields = context['fields'] if context else []
+        # fields = context['fields'] if context else []
         pad_bbox = np.zeros((num_max, 4), dtype=np.float32)
         if gt_num > 0:
             pad_bbox[:gt_num, :] = bbox[:gt_num, :]
         sample['gt_bbox'] = pad_bbox
-        if 'gt_class' in fields:
-            pad_class = np.zeros((num_max), dtype=np.int32)
+        if 'gt_class' in sample:
+            pad_class = np.zeros((num_max, ), dtype=np.int32)
             if gt_num > 0:
                 pad_class[:gt_num] = sample['gt_class'][:gt_num, 0]
             sample['gt_class'] = pad_class
-        if 'gt_score' in fields:
-            pad_score = np.zeros((num_max), dtype=np.float32)
+        if 'gt_score' in sample:
+            pad_score = np.zeros((num_max, ), dtype=np.float32)
             if gt_num > 0:
                 pad_score[:gt_num] = sample['gt_score'][:gt_num, 0]
             sample['gt_score'] = pad_score
         # in training, for example in op ExpandImage,
         # the bbox and gt_class is expandded, but the difficult is not,
         # so, judging by it's length
-        if 'is_difficult' in fields:
-            pad_diff = np.zeros((num_max), dtype=np.int32)
+        if 'is_difficult' in sample:
+            pad_diff = np.zeros((num_max, ), dtype=np.int32)
             if gt_num > 0:
                 pad_diff[:gt_num] = sample['difficult'][:gt_num, 0]
             sample['difficult'] = pad_diff
@@ -1751,9 +1811,9 @@ class Pad(BaseOperator):
         x, y = offsets
         im_h, im_w = im_size
         h, w = size
-        canvas = np.ones((h, w, 3), dtype=np.uint8)
-        canvas *= np.array(self.fill_value, dtype=np.uint8)
-        canvas[y:y + im_h, x:x + im_w, :] = image.astype(np.uint8)
+        canvas = np.ones((h, w, 3), dtype=np.float32)
+        canvas *= np.array(self.fill_value, dtype=np.float32)
+        canvas[y:y + im_h, x:x + im_w, :] = image.astype(np.float32)
         return canvas
 
     def apply(self, sample, context=None):
diff --git a/ppdet/modeling/__init__.py b/ppdet/modeling/__init__.py
index 01b1d2adbdd30f6849ee8cd968dc1c46310bd6b2..ab7ca0ff1430e88e62bd2ad01b8eb1c2bee57449 100644
--- a/ppdet/modeling/__init__.py
+++ b/ppdet/modeling/__init__.py
@@ -8,6 +8,7 @@ from . import loss
 from . import architecture
 from . import post_process
 from . import layers
+from . import utils
 
 from .ops import *
 from .bbox import *
@@ -19,3 +20,4 @@ from .loss import *
 from .architecture import *
 from .post_process import *
 from .layers import *
+from .utils import *
diff --git a/ppdet/modeling/architecture/yolo.py b/ppdet/modeling/architecture/yolo.py
index 1d21d17041809bdd1ee7324ba1c86ee74d696be0..e63ec8bd2c994e31e1ce0936075c5a0fd6a257f6 100644
--- a/ppdet/modeling/architecture/yolo.py
+++ b/ppdet/modeling/architecture/yolo.py
@@ -40,13 +40,13 @@ class YOLOv3(BaseArch):
         self.yolo_head_outs = self.yolo_head(body_feats)
 
     def get_loss(self, ):
-        loss = self.yolo_head.get_loss(self.inputs, self.yolo_head_outs)
+        loss = self.yolo_head.get_loss(self.yolo_head_outs, self.inputs)
         return loss
 
     def get_pred(self, ):
-        bbox, bbox_num = self.post_process(self.yolo_head_outs,
-                                           self.yolo_head.mask_anchors,
-                                           self.inputs['im_size'])
+        bbox, bbox_num = self.post_process(
+            self.yolo_head_outs, self.yolo_head.mask_anchors,
+            self.inputs['im_shape'], self.inputs['scale_factor'])
         outs = {
             "bbox": bbox.numpy(),
             "bbox_num": bbox_num.numpy(),
diff --git a/ppdet/modeling/backbone/darknet.py b/ppdet/modeling/backbone/darknet.py
index b1e386caebe2926ea191e15a1887cb74b3dc334d..a1788eeac5f349b395912c653beda70f877e28b7 100755
--- a/ppdet/modeling/backbone/darknet.py
+++ b/ppdet/modeling/backbone/darknet.py
@@ -2,8 +2,9 @@ import paddle
 import paddle.nn as nn
 import paddle.nn.functional as F
 from paddle import ParamAttr
-from paddle.fluid.regularizer import L2Decay
+from paddle.regularizer import L2Decay
 from ppdet.core.workspace import register, serializable
+from ppdet.modeling.ops import BatchNorm
 
 __all__ = ['DarkNet', 'ConvBNLayer']
 
@@ -16,6 +17,7 @@ class ConvBNLayer(nn.Layer):
                  stride=1,
                  groups=1,
                  padding=0,
+                 norm_type='bn',
                  act="leaky",
                  name=None):
         super(ConvBNLayer, self).__init__()
@@ -29,14 +31,7 @@ class ConvBNLayer(nn.Layer):
             groups=groups,
             weight_attr=ParamAttr(name=name + '.conv.weights'),
             bias_attr=False)
-        bn_name = name + '.bn'
-        self.batch_norm = nn.BatchNorm2D(
-            ch_out,
-            weight_attr=ParamAttr(
-                name=bn_name + '.scale', regularizer=L2Decay(0.)),
-            bias_attr=ParamAttr(
-                name=bn_name + '.offset', regularizer=L2Decay(0.)))
-
+        self.batch_norm = BatchNorm(ch_out, norm_type=norm_type, name=name)
         self.act = act
 
     def forward(self, inputs):
@@ -54,6 +49,7 @@ class DownSample(nn.Layer):
                  filter_size=3,
                  stride=2,
                  padding=1,
+                 norm_type='bn',
                  name=None):
 
         super(DownSample, self).__init__()
@@ -64,6 +60,7 @@ class DownSample(nn.Layer):
             filter_size=filter_size,
             stride=stride,
             padding=padding,
+            norm_type=norm_type,
             name=name)
         self.ch_out = ch_out
 
@@ -73,7 +70,7 @@ class DownSample(nn.Layer):
 
 
 class BasicBlock(nn.Layer):
-    def __init__(self, ch_in, ch_out, name=None):
+    def __init__(self, ch_in, ch_out, norm_type='bn', name=None):
         super(BasicBlock, self).__init__()
 
         self.conv1 = ConvBNLayer(
@@ -82,6 +79,7 @@ class BasicBlock(nn.Layer):
             filter_size=1,
             stride=1,
             padding=0,
+            norm_type=norm_type,
             name=name + '.0')
         self.conv2 = ConvBNLayer(
             ch_in=ch_out,
@@ -89,6 +87,7 @@ class BasicBlock(nn.Layer):
             filter_size=3,
             stride=1,
             padding=1,
+            norm_type=norm_type,
             name=name + '.1')
 
     def forward(self, inputs):
@@ -99,16 +98,18 @@ class BasicBlock(nn.Layer):
 
 
 class Blocks(nn.Layer):
-    def __init__(self, ch_in, ch_out, count, name=None):
+    def __init__(self, ch_in, ch_out, count, norm_type='bn', name=None):
         super(Blocks, self).__init__()
 
-        self.basicblock0 = BasicBlock(ch_in, ch_out, name=name + '.0')
+        self.basicblock0 = BasicBlock(
+            ch_in, ch_out, norm_type=norm_type, name=name + '.0')
         self.res_out_list = []
         for i in range(1, count):
             block_name = '{}.{}'.format(name, i)
             res_out = self.add_sublayer(
-                block_name, BasicBlock(
-                    ch_out * 2, ch_out, name=block_name))
+                block_name,
+                BasicBlock(
+                    ch_out * 2, ch_out, norm_type=norm_type, name=block_name))
             self.res_out_list.append(res_out)
         self.ch_out = ch_out
 
@@ -125,11 +126,14 @@ DarkNet_cfg = {53: ([1, 2, 8, 8, 4])}
 @register
 @serializable
 class DarkNet(nn.Layer):
+    __shared__ = ['norm_type']
+
     def __init__(self,
                  depth=53,
                  freeze_at=-1,
                  return_idx=[2, 3, 4],
-                 num_stages=5):
+                 num_stages=5,
+                 norm_type='bn'):
         super(DarkNet, self).__init__()
         self.depth = depth
         self.freeze_at = freeze_at
@@ -143,10 +147,14 @@ class DarkNet(nn.Layer):
             filter_size=3,
             stride=1,
             padding=1,
+            norm_type=norm_type,
             name='yolo_input')
 
         self.downsample0 = DownSample(
-            ch_in=32, ch_out=32 * 2, name='yolo_input.downsample')
+            ch_in=32,
+            ch_out=32 * 2,
+            norm_type=norm_type,
+            name='yolo_input.downsample')
 
         self.darknet_conv_block_list = []
         self.downsample_list = []
@@ -154,8 +162,13 @@ class DarkNet(nn.Layer):
         for i, stage in enumerate(self.stages):
             name = 'stage.{}'.format(i)
             conv_block = self.add_sublayer(
-                name, Blocks(
-                    int(ch_in[i]), 32 * (2**i), stage, name=name))
+                name,
+                Blocks(
+                    int(ch_in[i]),
+                    32 * (2**i),
+                    stage,
+                    norm_type=norm_type,
+                    name=name))
             self.darknet_conv_block_list.append(conv_block)
         for i in range(num_stages - 1):
             down_name = 'stage.{}.downsample'.format(i)
@@ -164,6 +177,7 @@ class DarkNet(nn.Layer):
                 DownSample(
                     ch_in=32 * (2**(i + 1)),
                     ch_out=32 * (2**(i + 2)),
+                    norm_type=norm_type,
                     name=down_name))
             self.downsample_list.append(downsample)
 
diff --git a/ppdet/modeling/head/yolo_head.py b/ppdet/modeling/head/yolo_head.py
index 2fa370b62c8edc66a002d8e5c933655042bfdd10..2814fb3b0d3bd002708b2ea17790870d0c0e1489 100644
--- a/ppdet/modeling/head/yolo_head.py
+++ b/ppdet/modeling/head/yolo_head.py
@@ -1,9 +1,8 @@
-import paddle.fluid as fluid
 import paddle
 import paddle.nn as nn
 import paddle.nn.functional as F
 from paddle import ParamAttr
-from paddle.fluid.regularizer import L2Decay
+from paddle.regularizer import L2Decay
 from ppdet.core.workspace import register
 from ..backbone.darknet import ConvBNLayer
 
@@ -14,24 +13,20 @@ class YOLOv3Head(nn.Layer):
     __inject__ = ['loss']
 
     def __init__(self,
-                 anchors=[
-                     10, 13, 16, 30, 33, 23, 30, 61, 62, 45, 59, 119, 116, 90,
-                     156, 198, 373, 326
-                 ],
+                 anchors=[[10, 13], [16, 30], [33, 23], [30, 61], [62, 45],
+                          [59, 119], [116, 90], [156, 198], [373, 326]],
                  anchor_masks=[[6, 7, 8], [3, 4, 5], [0, 1, 2]],
                  num_classes=80,
                  loss='YOLOv3Loss'):
         super(YOLOv3Head, self).__init__()
-        self.anchors = anchors
-        self.anchor_masks = anchor_masks
         self.num_classes = num_classes
         self.loss = loss
 
-        self.mask_anchors = self.parse_anchor(self.anchors, self.anchor_masks)
-        self.num_outputs = len(self.mask_anchors)
+        self.parse_anchor(anchors, anchor_masks)
+        self.num_outputs = len(self.anchors)
 
         self.yolo_outputs = []
-        for i in range(len(self.mask_anchors)):
+        for i in range(len(self.anchors)):
             num_filters = self.num_outputs * (self.num_classes + 5)
             name = 'yolo_output.{}'.format(i)
             yolo_output = self.add_sublayer(
@@ -48,24 +43,22 @@ class YOLOv3Head(nn.Layer):
             self.yolo_outputs.append(yolo_output)
 
     def parse_anchor(self, anchors, anchor_masks):
-        anchor_num = len(self.anchors)
-        mask_anchors = []
-        for i in range(len(self.anchor_masks)):
-            mask_anchor = []
-            for m in self.anchor_masks[i]:
-                assert m < anchor_num, "anchor mask index overflow"
-                mask_anchor.extend(self.anchors[2 * m:2 * m + 2])
-            mask_anchors.append(mask_anchor)
-
-        return mask_anchors
+        self.anchors = [[anchors[i] for i in mask] for mask in anchor_masks]
+        self.mask_anchors = []
+        anchor_num = len(anchors)
+        for masks in anchor_masks:
+            self.mask_anchors.append([])
+            for mask in masks:
+                assert mask < anchor_num, "anchor mask index overflow"
+                self.mask_anchors[-1].extend(anchors[mask])
 
     def forward(self, feats):
-        assert len(feats) == len(self.mask_anchors)
+        assert len(feats) == len(self.anchors)
         yolo_outputs = []
         for i, feat in enumerate(feats):
             yolo_output = self.yolo_outputs[i](feat)
             yolo_outputs.append(yolo_output)
         return yolo_outputs
 
-    def get_loss(self, inputs, head_outputs):
-        return self.loss(inputs, head_outputs, self.anchors, self.anchor_masks)
+    def get_loss(self, inputs, targets):
+        return self.loss(inputs, targets, self.anchors)
diff --git a/ppdet/modeling/layers.py b/ppdet/modeling/layers.py
index 029309504a39b77007076e0d75fab9148a5a9ff9..15176341ec273cf6a06530296652d71a66dd138d 100644
--- a/ppdet/modeling/layers.py
+++ b/ppdet/modeling/layers.py
@@ -407,10 +407,13 @@ class YOLOBox(object):
     def __call__(self, yolo_head_out, anchors, im_shape, scale_factor=None):
         boxes_list = []
         scores_list = []
+        im_shape = paddle.cast(im_shape, 'float32')
         if scale_factor is not None:
             origin_shape = im_shape / scale_factor
         else:
             origin_shape = im_shape
+
+        origin_shape = paddle.cast(origin_shape, 'int32')
         for i, head_out in enumerate(yolo_head_out):
             boxes, scores = ops.yolo_box(head_out, origin_shape, anchors[i],
                                          self.num_classes, self.conf_thresh,
diff --git a/ppdet/modeling/loss/__init__.py b/ppdet/modeling/loss/__init__.py
index f18cadcc87d994ac5462be5c4204f2eb01fc82f8..6d87bdc02f94ff6eb1e72f81fab717f3c001d427 100644
--- a/ppdet/modeling/loss/__init__.py
+++ b/ppdet/modeling/loss/__init__.py
@@ -13,5 +13,9 @@
 # limitations under the License.
 
 from . import yolo_loss
+from . import iou_aware_loss
+from . import iou_loss
 
 from .yolo_loss import *
+from .iou_aware_loss import *
+from .iou_loss import *
diff --git a/ppdet/modeling/loss/iou_aware_loss.py b/ppdet/modeling/loss/iou_aware_loss.py
new file mode 100644
index 0000000000000000000000000000000000000000..0e61883f9af496c6336ad682011f45dc974b0b36
--- /dev/null
+++ b/ppdet/modeling/loss/iou_aware_loss.py
@@ -0,0 +1,59 @@
+# Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import paddle.nn.functional as F
+from ppdet.core.workspace import register, serializable
+from .iou_loss import IouLoss
+from ..utils import xywh2xyxy, bbox_iou, decode_yolo
+
+
+@register
+@serializable
+class IouAwareLoss(IouLoss):
+    """
+    iou aware loss, see https://arxiv.org/abs/1912.05992
+    Args:
+        loss_weight (float): iou aware loss weight, default is 1.0
+        max_height (int): max height of input to support random shape input
+        max_width (int): max width of input to support random shape input
+    """
+
+    def __init__(
+            self,
+            loss_weight=1.0,
+            giou=False,
+            diou=False,
+            ciou=False, ):
+        super(IouAwareLoss, self).__init__(
+            loss_weight=loss_weight, giou=giou, diou=diou, ciou=ciou)
+
+    def __call__(self, ioup, pbox, gbox, anchor, downsample, scale=1.):
+        b = pbox.shape[0]
+        ioup = ioup.reshape((b, -1))
+        pbox = decode_yolo(pbox, anchor, downsample)
+        gbox = decode_yolo(gbox, anchor, downsample)
+        pbox = xywh2xyxy(pbox).reshape((b, -1, 4))
+        gbox = xywh2xyxy(gbox).reshape((b, -1, 4))
+        iou = bbox_iou(
+            pbox, gbox, giou=self.giou, diou=self.diou, ciou=self.ciou)
+        iou.stop_gradient = True
+
+        loss_iou_aware = F.binary_cross_entropy_with_logits(
+            ioup, iou, reduction='none')
+        loss_iou_aware = loss_iou_aware * self.loss_weight
+        return loss_iou_aware
diff --git a/ppdet/modeling/loss/iou_loss.py b/ppdet/modeling/loss/iou_loss.py
new file mode 100644
index 0000000000000000000000000000000000000000..97c59bf278c9d269d557eb434b87b0c65f632371
--- /dev/null
+++ b/ppdet/modeling/loss/iou_loss.py
@@ -0,0 +1,67 @@
+# Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import paddle
+import paddle.nn.functional as F
+from ppdet.core.workspace import register, serializable
+from ..utils import xywh2xyxy, bbox_iou, decode_yolo
+
+__all__ = ['IouLoss']
+
+
+@register
+@serializable
+class IouLoss(object):
+    """
+    iou loss, see https://arxiv.org/abs/1908.03851
+    loss = 1.0 - iou * iou
+    Args:
+        loss_weight (float): iou loss weight, default is 2.5
+        max_height (int): max height of input to support random shape input
+        max_width (int): max width of input to support random shape input
+        ciou_term (bool): whether to add ciou_term
+        loss_square (bool): whether to square the iou term
+    """
+
+    def __init__(self,
+                 loss_weight=2.5,
+                 giou=False,
+                 diou=False,
+                 ciou=False,
+                 loss_square=True):
+        self.loss_weight = loss_weight
+        self.giou = giou
+        self.diou = diou
+        self.ciou = ciou
+        self.loss_square = loss_square
+
+    def __call__(self, pbox, gbox, anchor, downsample, scale=1.):
+        b = pbox.shape[0]
+        pbox = decode_yolo(pbox, anchor, downsample)
+        gbox = decode_yolo(gbox, anchor, downsample)
+        pbox = xywh2xyxy(pbox).reshape((b, -1, 4))
+        gbox = xywh2xyxy(gbox).reshape((b, -1, 4))
+        iou = bbox_iou(
+            pbox, gbox, giou=self.giou, diou=self.diou, ciou=self.ciou)
+        if self.loss_square:
+            loss_iou = 1 - iou * iou
+        else:
+            loss_iou = 1 - iou
+
+        loss_iou = loss_iou * self.loss_weight
+        return loss_iou
diff --git a/ppdet/modeling/loss/yolo_loss.py b/ppdet/modeling/loss/yolo_loss.py
index bfef53a1dd0a3787200e22d34170d58f62afafd3..51bc490cb9a08220f6eade39444d52e31a6e755b 100644
--- a/ppdet/modeling/loss/yolo_loss.py
+++ b/ppdet/modeling/loss/yolo_loss.py
@@ -12,54 +12,156 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import paddle.fluid as fluid
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
 import paddle
 import paddle.nn as nn
 import paddle.nn.functional as F
-from paddle import ParamAttr
-from paddle.fluid.regularizer import L2Decay
 from ppdet.core.workspace import register
-from ..backbone.darknet import ConvBNLayer
+
+from ..utils import decode_yolo, xywh2xyxy, iou_similarity
 
 __all__ = ['YOLOv3Loss']
 
 
 @register
 class YOLOv3Loss(nn.Layer):
+
+    __inject__ = ['iou_loss', 'iou_aware_loss']
     __shared__ = ['num_classes']
 
     def __init__(self,
                  num_classes=80,
                  ignore_thresh=0.7,
                  label_smooth=False,
-                 downsample=32,
-                 use_fine_grained_loss=False):
+                 downsample=[32, 16, 8],
+                 scale_x_y=1.,
+                 iou_loss=None,
+                 iou_aware_loss=None):
         super(YOLOv3Loss, self).__init__()
         self.num_classes = num_classes
         self.ignore_thresh = ignore_thresh
         self.label_smooth = label_smooth
         self.downsample = downsample
-        self.use_fine_grained_loss = use_fine_grained_loss
-
-    def forward(self, inputs, head_outputs, anchors, anchor_masks):
-        if self.use_fine_grained_loss:
-            raise NotImplementedError(
-                "fine grained loss not implement currently")
-
-        yolo_losses = []
-        for i, out in enumerate(head_outputs):
-            loss = fluid.layers.yolov3_loss(
-                x=out,
-                gt_box=inputs['gt_bbox'],
-                gt_label=inputs['gt_class'],
-                gt_score=inputs['gt_score'],
-                anchors=anchors,
-                anchor_mask=anchor_masks[i],
-                class_num=self.num_classes,
-                ignore_thresh=self.ignore_thresh,
-                downsample_ratio=self.downsample // 2**i,
-                use_label_smooth=self.label_smooth,
-                name='yolo_loss_' + str(i))
-            loss = paddle.mean(loss)
-            yolo_losses.append(loss)
-        return {'loss': sum(yolo_losses)}
+        self.scale_x_y = scale_x_y
+        self.iou_loss = iou_loss
+        self.iou_aware_loss = iou_aware_loss
+
+    def obj_loss(self, pbox, gbox, pobj, tobj, anchor, downsample):
+        b, h, w, na = pbox.shape[:4]
+        pbox = decode_yolo(pbox, anchor, downsample)
+        pbox = pbox.reshape((b, -1, 4))
+        pbox = xywh2xyxy(pbox)
+        gbox = xywh2xyxy(gbox)
+
+        iou = iou_similarity(pbox, gbox)
+        iou.stop_gradient = True
+        iou_max = iou.max(2)  # [N, M1]
+        iou_mask = paddle.cast(iou_max <= self.ignore_thresh, dtype=pbox.dtype)
+        iou_mask.stop_gradient = True
+
+        pobj = pobj.reshape((b, -1))
+        tobj = tobj.reshape((b, -1))
+        obj_mask = paddle.cast(tobj > 0, dtype=pbox.dtype)
+        obj_mask.stop_gradient = True
+
+        loss_obj = F.binary_cross_entropy_with_logits(
+            pobj, obj_mask, reduction='none')
+        loss_obj_pos = (loss_obj * tobj)
+        loss_obj_neg = (loss_obj * (1 - obj_mask) * iou_mask)
+        return loss_obj_pos + loss_obj_neg
+
+    def cls_loss(self, pcls, tcls):
+        if self.label_smooth:
+            delta = min(1. / self.num_classes, 1. / 40)
+            pos, neg = 1 - delta, delta
+            # 1 for positive, 0 for negative
+            tcls = pos * paddle.cast(
+                tcls > 0., dtype=tcls.dtype) + neg * paddle.cast(
+                    tcls <= 0., dtype=tcls.dtype)
+
+        loss_cls = F.binary_cross_entropy_with_logits(
+            pcls, tcls, reduction='none')
+        return loss_cls
+
+    def yolov3_loss(self, x, t, gt_box, anchor, downsample, scale=1.,
+                    eps=1e-10):
+        na = len(anchor)
+        b, c, h, w = x.shape
+        no = c // na
+        x = x.reshape((b, na, no, h, w)).transpose((0, 3, 4, 1, 2))
+
+        xy, wh, obj = x[:, :, :, :, 0:2], x[:, :, :, :, 2:4], x[:, :, :, :, 4:5]
+        if self.iou_aware_loss:
+            ioup, pcls = x[:, :, :, :, 5:6], x[:, :, :, :, 6:]
+        else:
+            pcls = x[:, :, :, :, 5:]
+
+        t = t.transpose((0, 3, 4, 1, 2))
+        txy, twh, tscale = t[:, :, :, :, 0:2], t[:, :, :, :, 2:4], t[:, :, :, :,
+                                                                     4:5]
+        tobj, tcls = t[:, :, :, :, 5:6], t[:, :, :, :, 6:]
+
+        tscale_obj = tscale * tobj
+        loss = dict()
+        if abs(scale - 1.) < eps:
+            loss_xy = tscale_obj * F.binary_cross_entropy_with_logits(
+                xy, txy, reduction='none')
+        else:
+            xy = scale * F.sigmoid(xy) - 0.5 * (scale - 1.)
+            loss_xy = tscale_obj * paddle.abs(xy - txy)
+
+        loss_xy = loss_xy.sum([1, 2, 3, 4]).mean()
+        loss_wh = tscale_obj * paddle.abs(wh - twh)
+        loss_wh = loss_wh.sum([1, 2, 3, 4]).mean()
+
+        loss['loss_loc'] = loss_xy + loss_wh
+
+        x[:, :, :, :, 0:2] = scale * F.sigmoid(x[:, :, :, :, 0:2]) - 0.5 * (
+            scale - 1.)
+        box, tbox = x[:, :, :, :, 0:4], t[:, :, :, :, 0:4]
+        if self.iou_loss is not None:
+            # box and tbox will not change though they are modified in self.iou_loss function, so no need to clone
+            loss_iou = self.iou_loss(box, tbox, anchor, downsample, scale)
+            loss_iou = loss_iou * tscale_obj.reshape((b, -1))
+            loss_iou = loss_iou.sum(-1).mean()
+            loss['loss_iou'] = loss_iou
+
+        if self.iou_aware_loss is not None:
+            # box and tbox will not change though they are modified in self.iou_aware_loss function, so no need to clone
+            loss_iou_aware = self.iou_aware_loss(ioup, box, tbox, anchor,
+                                                 downsample, scale)
+            loss_iou_aware = loss_iou_aware * tobj.reshape((b, -1))
+            loss_iou_aware = loss_iou_aware.sum(-1).mean()
+            loss['loss_iou_aware'] = loss_iou_aware
+
+        loss_obj = self.obj_loss(box, gt_box, obj, tobj, anchor, downsample)
+        loss_obj = loss_obj.sum(-1).mean()
+        loss['loss_obj'] = loss_obj
+        loss_cls = self.cls_loss(pcls, tcls) * tobj
+        loss_cls = loss_cls.sum([1, 2, 3, 4]).mean()
+        loss['loss_cls'] = loss_cls
+        return loss
+
+    def forward(self, inputs, targets, anchors):
+        np = len(inputs)
+        gt_targets = [targets['target{}'.format(i)] for i in range(np)]
+        gt_box = targets['gt_bbox']
+        yolo_losses = dict()
+        for x, t, anchor, downsample in zip(inputs, gt_targets, anchors,
+                                            self.downsample):
+            yolo_loss = self.yolov3_loss(x, t, gt_box, anchor, downsample)
+            for k, v in yolo_loss.items():
+                if k in yolo_losses:
+                    yolo_losses[k] += v
+                else:
+                    yolo_losses[k] = v
+
+        loss = 0
+        for k, v in yolo_losses.items():
+            loss += v
+
+        yolo_losses['loss'] = loss
+        return yolo_losses
diff --git a/ppdet/modeling/neck/yolo_fpn.py b/ppdet/modeling/neck/yolo_fpn.py
index a7cfa349f805a8da0711b89c1d6d960df0bcc0b6..bd49069977aeb32dc17e431b1831729d9d7a9250 100644
--- a/ppdet/modeling/neck/yolo_fpn.py
+++ b/ppdet/modeling/neck/yolo_fpn.py
@@ -21,7 +21,7 @@ from ..backbone.darknet import ConvBNLayer
 
 
 class YoloDetBlock(nn.Layer):
-    def __init__(self, ch_in, channel, name):
+    def __init__(self, ch_in, channel, norm_type, name):
         super(YoloDetBlock, self).__init__()
         self.ch_in = ch_in
         self.channel = channel
@@ -45,6 +45,7 @@ class YoloDetBlock(nn.Layer):
                     ch_out=ch_out,
                     filter_size=filter_size,
                     padding=(filter_size - 1) // 2,
+                    norm_type=norm_type,
                     name=name + post_name))
 
         self.tip = ConvBNLayer(
@@ -52,6 +53,7 @@ class YoloDetBlock(nn.Layer):
             ch_out=channel * 2,
             filter_size=3,
             padding=1,
+            norm_type=norm_type,
             name=name + '.tip')
 
     def forward(self, inputs):
@@ -63,7 +65,9 @@ class YoloDetBlock(nn.Layer):
 @register
 @serializable
 class YOLOv3FPN(nn.Layer):
-    def __init__(self, feat_channels=[1024, 768, 384]):
+    __shared__ = ['norm_type']
+
+    def __init__(self, feat_channels=[1024, 768, 384], norm_type='bn'):
         super(YOLOv3FPN, self).__init__()
         assert len(feat_channels) > 0, "feat_channels length should > 0"
         self.feat_channels = feat_channels
@@ -75,7 +79,10 @@ class YOLOv3FPN(nn.Layer):
             yolo_block = self.add_sublayer(
                 name,
                 YoloDetBlock(
-                    feat_channels[i], channel=512 // (2**i), name=name))
+                    feat_channels[i],
+                    channel=512 // (2**i),
+                    norm_type=norm_type,
+                    name=name))
             self.yolo_blocks.append(yolo_block)
 
             if i < self.num_blocks - 1:
@@ -88,6 +95,7 @@ class YOLOv3FPN(nn.Layer):
                         filter_size=1,
                         stride=1,
                         padding=0,
+                        norm_type=norm_type,
                         name=name))
                 self.routes.append(route)
 
diff --git a/ppdet/modeling/ops.py b/ppdet/modeling/ops.py
index 6c8a55204e999aaf32cd8883718c3e6f4dfd3797..88a17437740669ed5b32f7f3361bb536abc9a829 100644
--- a/ppdet/modeling/ops.py
+++ b/ppdet/modeling/ops.py
@@ -14,6 +14,9 @@
 
 import paddle
 import paddle.nn.functional as F
+import paddle.nn as nn
+from paddle import ParamAttr
+from paddle.regularizer import L2Decay
 
 from paddle.fluid.framework import Variable, in_dygraph_mode
 from paddle.fluid import core
@@ -26,21 +29,33 @@ import numpy as np
 from functools import reduce
 
 __all__ = [
-    'roi_pool',
-    'roi_align',
-    'prior_box',
-    'anchor_generator',
-    'generate_proposals',
-    'iou_similarity',
-    'box_coder',
-    'yolo_box',
-    'multiclass_nms',
-    'distribute_fpn_proposals',
-    'collect_fpn_proposals',
-    'matrix_nms',
+    'roi_pool', 'roi_align', 'prior_box', 'anchor_generator',
+    'generate_proposals', 'iou_similarity', 'box_coder', 'yolo_box',
+    'multiclass_nms', 'distribute_fpn_proposals', 'collect_fpn_proposals',
+    'matrix_nms', 'BatchNorm'
 ]
 
 
+class BatchNorm(nn.Layer):
+    def __init__(self, ch, norm_type='bn', name=None):
+        super(BatchNorm, self).__init__()
+        bn_name = name + '.bn'
+        if norm_type == 'sync_bn':
+            batch_norm = nn.SyncBatchNorm
+        else:
+            batch_norm = nn.BatchNorm2D
+
+        self.batch_norm = batch_norm(
+            ch,
+            weight_attr=ParamAttr(
+                name=bn_name + '.scale', regularizer=L2Decay(0.)),
+            bias_attr=ParamAttr(
+                name=bn_name + '.offset', regularizer=L2Decay(0.)))
+
+    def forward(self, x):
+        return self.batch_norm(x)
+
+
 def roi_pool(input,
              rois,
              output_size,
diff --git a/ppdet/modeling/post_process.py b/ppdet/modeling/post_process.py
index 5dd686d3a1e3733d60e5163a3de3c3b0a94c34cf..fab68eeae4d2ba5bce55f590a946619d8666efb6 100644
--- a/ppdet/modeling/post_process.py
+++ b/ppdet/modeling/post_process.py
@@ -1,5 +1,4 @@
 import numpy as np
-import paddle.fluid as fluid
 import paddle
 import paddle.nn as nn
 import paddle.nn.functional as F
diff --git a/ppdet/modeling/tests/test_transfrom.py b/ppdet/modeling/tests/test_transfrom.py
new file mode 100644
index 0000000000000000000000000000000000000000..b98710467e31747342d71b9050e3188ecbac4f5a
--- /dev/null
+++ b/ppdet/modeling/tests/test_transfrom.py
@@ -0,0 +1,240 @@
+from __future__ import print_function
+import random
+import unittest
+import numpy as np
+import copy
+# add python path of PadleDetection to sys.path
+import os
+import sys
+parent_path = os.path.abspath(os.path.join(__file__, *(['..'] * 4)))
+if parent_path not in sys.path:
+    sys.path.append(parent_path)
+
+from ppdet.data.transform import *
+
+
+def gen_sample(h, w, nt, nc, random_score=True, channel_first=False):
+    im = np.random.randint(0, 256, size=(h, w, 3)).astype('float32')
+    if channel_first:
+        im = im.transpose((2, 0, 1))
+    gt_bbox = np.random.random(size=(nt, 4)).astype('float32')
+    gt_class = np.random.randint(0, nc, size=(nt, 1)).astype('int32')
+    if random_score:
+        gt_score = np.random.random(size=(nt, 1))
+    else:
+        gt_score = np.ones(shape=(nt, 1)).astype('float32')
+    is_crowd = np.zeros_like(gt_class)
+    sample = {
+        'image': im,
+        'gt_bbox': gt_bbox,
+        'gt_class': gt_class,
+        'gt_score': gt_score,
+        'is_crowd': is_crowd,
+        'h': h,
+        'w': w
+    }
+    return sample
+
+
+class TestTransformOp(unittest.TestCase):
+    def setUp(self):
+        self.h, self.w = np.random.randint(1, 1024, size=2)
+        self.nt = np.random.randint(1, 50)
+        self.nc = 80
+
+    def assertAllClose(self, x, y, msg, atol=1e-5, rtol=1e-3):
+        self.assertTrue(np.allclose(x, y, atol=atol, rtol=rtol), msg=msg)
+
+
+class TestResizeOp(TestTransformOp):
+    def test_resize(self):
+        sample = gen_sample(self.h, self.w, self.nt, self.nc)
+        orig_op = Resize(target_dim=608, interp=2)
+        curr_op = ResizeOp(target_size=608, keep_ratio=False, interp=2)
+        orig_res = orig_op(copy.deepcopy(sample))
+        curr_res = curr_op(copy.deepcopy(sample))
+        fields = ['image', 'gt_bbox', 'gt_class', 'gt_score']
+        for k in fields:
+            self.assertAllClose(orig_res[k], curr_res[k], msg=k)
+
+
+# only for specified random seed
+# class TestMixupOp(TestTransformOp):
+#     def setUp(self):
+#         self.h, self.w = np.random.randint(1024, size=2)
+#         self.nt = np.random.randint(50)
+#         self.nc = 80
+
+#     def test_mixup(self):
+#         curr_sample = [gen_sample(self.h, self.w, self.nt, self.nc) for _ in range(2)]
+#         orig_sample = copy.deepcopy(curr_sample[0])
+#         orig_sample['mixup'] = copy.deepcopy(curr_sample[1])
+#         orig_op = MixupImage(alpha=1.5, beta=1.5)
+#         curr_op = MixupOp(alpha=1.5, beta=1.5)
+#         orig_res = orig_op(orig_sample)
+#         curr_res = curr_op(curr_sample)
+#         fields = ['image', 'gt_bbox', 'gt_class', 'gt_score']
+#         for k in fields:
+#             self.assertAllClose(orig_res[k], curr_res[k], msg=k)
+
+# only for specified random seed
+# class TestRandomDistortOp(TestTransformOp):
+
+#     def test_random_distort(self):
+#         sample = gen_sample(self.h, self.w, self.nt, self.nc)
+#         orig_op = ColorDistort(hsv_format=True, random_apply=False)
+#         curr_op = RandomDistortOp(random_apply=False)
+#         orig_res = orig_op(copy.deepcopy(sample))
+#         curr_res = curr_op(copy.deepcopy(sample))
+#         fields = ['image', 'gt_bbox', 'gt_class', 'gt_score']
+#         for k in fields:
+#             self.assertAllClose(orig_res[k], curr_res[k], msg=k)
+
+# only for specified random seed
+# class TestRandomExpandOp(TestTransformOp):
+
+#     def test_random_expand(self):
+#         sample = gen_sample(self.h, self.w, self.nt, self.nc)
+#         orig_op = RandomExpand(fill_value=[123.675, 116.28, 103.53])
+#         curr_op = RandomExpandOp(fill_value=[123.675, 116.28, 103.53])
+#         orig_res = orig_op(copy.deepcopy(sample))
+#         curr_res = curr_op(copy.deepcopy(sample))
+#         fields = ['image', 'gt_bbox', 'gt_class', 'gt_score']
+#         for k in fields:
+#             self.assertAllClose(orig_res[k], curr_res[k], msg=k)
+
+# only for specified random seed
+# class TestRandomCropOp(TestTransformOp):
+
+#     def test_random_crop(self):
+#         sample = gen_sample(self.h, self.w, self.nt, self.nc)
+#         orig_op = RandomCrop()
+#         curr_op = RandomCropOp()
+#         orig_res = orig_op(copy.deepcopy(sample))
+#         curr_res = curr_op(copy.deepcopy(sample))
+#         fields = ['image', 'gt_bbox', 'gt_class', 'gt_score']
+#         for k in fields:
+#             self.assertAllClose(orig_res[k], curr_res[k], msg=k)
+
+# only for specified random seed
+# class TestRandomFlipOp(TestTransformOp):
+
+#     def test_random_flip(self):
+#         sample = gen_sample(self.h, self.w, self.nt, self.nc)
+#         orig_op = RandomFlipImage(is_normalized=False)
+#         curr_op = RandomFlipOp()
+#         orig_res = orig_op(copy.deepcopy(sample))
+#         curr_res = curr_op(copy.deepcopy(sample))
+#         fields = ['image', 'gt_bbox', 'gt_class', 'gt_score']
+#         for k in fields:
+#             self.assertAllClose(orig_res[k], curr_res[k], msg=k)
+
+# only for specified random seed
+# class TestBatchRandomResizeOp(TestTransformOp):
+
+#     def test_batch_random_resize(self):
+#         sample = [gen_sample(self.h, self.w, self.nt, self.nc) for _ in range(10)]
+#         orig_op = RandomShape(sizes=[320, 352, 384, 416, 448, 480, 512, 544, 576, 608], random_inter=True, resize_box=True)
+#         curr_op = BatchRandomResizeOp(target_size=[320, 352, 384, 416, 448, 480, 512, 544, 576, 608], random_size=True, random_interp=True, keep_ratio=False)
+#         orig_ress = orig_op(copy.deepcopy(sample))
+#         curr_ress = curr_op(copy.deepcopy(sample))
+#         fields = ['image', 'gt_bbox', 'gt_class', 'gt_score']
+#         for orig_res, curr_res in zip(orig_ress, curr_ress):
+#             for k in fields:
+#                 self.assertAllClose(orig_res[k], curr_res[k], msg=k)
+
+
+class TestNormalizeBoxOp(TestTransformOp):
+    def test_normalize_box(self):
+        sample = gen_sample(self.h, self.w, self.nt, self.nc)
+        orig_op = NormalizeBox()
+        curr_op = NormalizeBoxOp()
+        orig_res = orig_op(copy.deepcopy(sample))
+        curr_res = curr_op(copy.deepcopy(sample))
+        fields = ['image', 'gt_bbox', 'gt_class', 'gt_score']
+        for k in fields:
+            self.assertAllClose(orig_res[k], curr_res[k], msg=k)
+
+
+class TestPadBoxOp(TestTransformOp):
+    def test_pad_box(self):
+        sample = gen_sample(self.h, self.w, self.nt, self.nc)
+        orig_op = PadBox(num_max_boxes=50)
+        curr_op = PadBoxOp(num_max_boxes=50)
+        orig_res = orig_op(copy.deepcopy(sample))
+        curr_res = curr_op(copy.deepcopy(sample))
+        fields = ['image', 'gt_bbox', 'gt_class', 'gt_score']
+        for k in fields:
+            self.assertAllClose(orig_res[k], curr_res[k], msg=k)
+
+
+class TestBboxXYXY2XYWHOp(TestTransformOp):
+    def test_bbox_xyxy2xywh(self):
+        sample = gen_sample(self.h, self.w, self.nt, self.nc)
+        orig_op = BboxXYXY2XYWH()
+        curr_op = BboxXYXY2XYWHOp()
+        orig_res = orig_op(copy.deepcopy(sample))
+        curr_res = curr_op(copy.deepcopy(sample))
+        fields = ['image', 'gt_bbox', 'gt_class', 'gt_score']
+        for k in fields:
+            self.assertAllClose(orig_res[k], curr_res[k], msg=k)
+
+
+class TestNormalizeImageOp(TestTransformOp):
+    def test_normalize_image(self):
+        sample = gen_sample(self.h, self.w, self.nt, self.nc)
+        orig_op = NormalizeImage(
+            mean=[0.485, 0.456, 0.406],
+            std=[0.229, 0.224, 0.225],
+            is_scale=True,
+            is_channel_first=False)
+        curr_op = NormalizeImageOp(
+            mean=[0.485, 0.456, 0.406],
+            std=[0.229, 0.224, 0.225],
+            is_scale=True)
+        orig_res = orig_op(copy.deepcopy(sample))
+        curr_res = curr_op(copy.deepcopy(sample))
+        fields = ['image', 'gt_bbox', 'gt_class', 'gt_score']
+        for k in fields:
+            self.assertAllClose(orig_res[k], curr_res[k], msg=k)
+
+
+class TestPermuteOp(TestTransformOp):
+    def test_permute(self):
+        sample = gen_sample(self.h, self.w, self.nt, self.nc)
+        orig_op = Permute(to_bgr=False, channel_first=True)
+        curr_op = PermuteOp()
+        orig_res = orig_op(copy.deepcopy(sample))
+        curr_res = curr_op(copy.deepcopy(sample))
+        fields = ['image', 'gt_bbox', 'gt_class', 'gt_score']
+        for k in fields:
+            self.assertAllClose(orig_res[k], curr_res[k], msg=k)
+
+
+class TestGt2YoloTargetOp(TestTransformOp):
+    def test_gt2yolotarget(self):
+        sample = [
+            gen_sample(
+                self.h, self.w, self.nt, self.nc, channel_first=True)
+            for _ in range(10)
+        ]
+        orig_op = Gt2YoloTarget(
+            anchor_masks=[[6, 7, 8], [3, 4, 5], [0, 1, 2]],
+            anchors=[[10, 13], [16, 30], [33, 23], [30, 61], [62, 45],
+                     [59, 119], [116, 90], [156, 198], [373, 326]],
+            downsample_ratios=[32, 16, 8])
+        curr_op = Gt2YoloTargetOp(
+            anchor_masks=[[6, 7, 8], [3, 4, 5], [0, 1, 2]],
+            anchors=[[10, 13], [16, 30], [33, 23], [30, 61], [62, 45],
+                     [59, 119], [116, 90], [156, 198], [373, 326]],
+            downsample_ratios=[32, 16, 8])
+        orig_ress = orig_op(copy.deepcopy(sample))
+        curr_ress = curr_op(copy.deepcopy(sample))
+        fields = ['image', 'gt_bbox', 'gt_class', 'gt_score']
+        for orig_res, curr_res in zip(orig_ress, curr_ress):
+            for k in fields:
+                self.assertAllClose(orig_res[k], curr_res[k], msg=k)
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/ppdet/modeling/tests/test_yolov3_loss.py b/ppdet/modeling/tests/test_yolov3_loss.py
new file mode 100644
index 0000000000000000000000000000000000000000..885ae734077487f0f238c0273268391b46823ab8
--- /dev/null
+++ b/ppdet/modeling/tests/test_yolov3_loss.py
@@ -0,0 +1,419 @@
+#   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import division
+
+import unittest
+import numpy as np
+from scipy.special import logit
+from scipy.special import expit
+
+import paddle
+from paddle import fluid
+from paddle.fluid import core
+# add python path of PadleDetection to sys.path
+import os
+import sys
+parent_path = os.path.abspath(os.path.join(__file__, *(['..'] * 4)))
+if parent_path not in sys.path:
+    sys.path.append(parent_path)
+
+from ppdet.modeling.loss import YOLOv3Loss
+from ppdet.data.transform.op_helper import jaccard_overlap
+import random
+import numpy as np
+
+
+def _split_ioup(output, an_num, num_classes):
+    """
+    Split output feature map to output, predicted iou
+    along channel dimension
+    """
+    ioup = fluid.layers.slice(output, axes=[1], starts=[0], ends=[an_num])
+    ioup = fluid.layers.sigmoid(ioup)
+    oriout = fluid.layers.slice(
+        output, axes=[1], starts=[an_num], ends=[an_num * (num_classes + 6)])
+    return (ioup, oriout)
+
+
+def _split_output(output, an_num, num_classes):
+    """
+    Split output feature map to x, y, w, h, objectness, classification
+    along channel dimension
+    """
+    x = fluid.layers.strided_slice(
+        output,
+        axes=[1],
+        starts=[0],
+        ends=[output.shape[1]],
+        strides=[5 + num_classes])
+    y = fluid.layers.strided_slice(
+        output,
+        axes=[1],
+        starts=[1],
+        ends=[output.shape[1]],
+        strides=[5 + num_classes])
+    w = fluid.layers.strided_slice(
+        output,
+        axes=[1],
+        starts=[2],
+        ends=[output.shape[1]],
+        strides=[5 + num_classes])
+    h = fluid.layers.strided_slice(
+        output,
+        axes=[1],
+        starts=[3],
+        ends=[output.shape[1]],
+        strides=[5 + num_classes])
+    obj = fluid.layers.strided_slice(
+        output,
+        axes=[1],
+        starts=[4],
+        ends=[output.shape[1]],
+        strides=[5 + num_classes])
+    clss = []
+    stride = output.shape[1] // an_num
+    for m in range(an_num):
+        clss.append(
+            fluid.layers.slice(
+                output,
+                axes=[1],
+                starts=[stride * m + 5],
+                ends=[stride * m + 5 + num_classes]))
+    cls = fluid.layers.transpose(
+        fluid.layers.stack(
+            clss, axis=1), perm=[0, 1, 3, 4, 2])
+    return (x, y, w, h, obj, cls)
+
+
+def _split_target(target):
+    """
+    split target to x, y, w, h, objectness, classification
+    along dimension 2
+    target is in shape [N, an_num, 6 + class_num, H, W]
+    """
+    tx = target[:, :, 0, :, :]
+    ty = target[:, :, 1, :, :]
+    tw = target[:, :, 2, :, :]
+    th = target[:, :, 3, :, :]
+    tscale = target[:, :, 4, :, :]
+    tobj = target[:, :, 5, :, :]
+    tcls = fluid.layers.transpose(target[:, :, 6:, :, :], perm=[0, 1, 3, 4, 2])
+    tcls.stop_gradient = True
+    return (tx, ty, tw, th, tscale, tobj, tcls)
+
+
+def _calc_obj_loss(output, obj, tobj, gt_box, batch_size, anchors, num_classes,
+                   downsample, ignore_thresh, scale_x_y):
+    # A prediction bbox overlap any gt_bbox over ignore_thresh, 
+    # objectness loss will be ignored, process as follows:
+    # 1. get pred bbox, which is same with YOLOv3 infer mode, use yolo_box here
+    # NOTE: img_size is set as 1.0 to get noramlized pred bbox
+    bbox, prob = fluid.layers.yolo_box(
+        x=output,
+        img_size=fluid.layers.ones(
+            shape=[batch_size, 2], dtype="int32"),
+        anchors=anchors,
+        class_num=num_classes,
+        conf_thresh=0.,
+        downsample_ratio=downsample,
+        clip_bbox=False,
+        scale_x_y=scale_x_y)
+    # 2. split pred bbox and gt bbox by sample, calculate IoU between pred bbox
+    #    and gt bbox in each sample
+    if batch_size > 1:
+        preds = fluid.layers.split(bbox, batch_size, dim=0)
+        gts = fluid.layers.split(gt_box, batch_size, dim=0)
+    else:
+        preds = [bbox]
+        gts = [gt_box]
+        probs = [prob]
+    ious = []
+    for pred, gt in zip(preds, gts):
+
+        def box_xywh2xyxy(box):
+            x = box[:, 0]
+            y = box[:, 1]
+            w = box[:, 2]
+            h = box[:, 3]
+            return fluid.layers.stack(
+                [
+                    x - w / 2.,
+                    y - h / 2.,
+                    x + w / 2.,
+                    y + h / 2.,
+                ], axis=1)
+
+        pred = fluid.layers.squeeze(pred, axes=[0])
+        gt = box_xywh2xyxy(fluid.layers.squeeze(gt, axes=[0]))
+        ious.append(fluid.layers.iou_similarity(pred, gt))
+    iou = fluid.layers.stack(ious, axis=0)
+    # 3. Get iou_mask by IoU between gt bbox and prediction bbox,
+    #    Get obj_mask by tobj(holds gt_score), calculate objectness loss
+    max_iou = fluid.layers.reduce_max(iou, dim=-1)
+    iou_mask = fluid.layers.cast(max_iou <= ignore_thresh, dtype="float32")
+    output_shape = fluid.layers.shape(output)
+    an_num = len(anchors) // 2
+    iou_mask = fluid.layers.reshape(iou_mask, (-1, an_num, output_shape[2],
+                                               output_shape[3]))
+    iou_mask.stop_gradient = True
+    # NOTE: tobj holds gt_score, obj_mask holds object existence mask
+    obj_mask = fluid.layers.cast(tobj > 0., dtype="float32")
+    obj_mask.stop_gradient = True
+    # For positive objectness grids, objectness loss should be calculated
+    # For negative objectness grids, objectness loss is calculated only iou_mask == 1.0
+    loss_obj = fluid.layers.sigmoid_cross_entropy_with_logits(obj, obj_mask)
+    loss_obj_pos = fluid.layers.reduce_sum(loss_obj * tobj, dim=[1, 2, 3])
+    loss_obj_neg = fluid.layers.reduce_sum(
+        loss_obj * (1.0 - obj_mask) * iou_mask, dim=[1, 2, 3])
+    return loss_obj_pos, loss_obj_neg
+
+
+def fine_grained_loss(output,
+                      target,
+                      gt_box,
+                      batch_size,
+                      num_classes,
+                      anchors,
+                      ignore_thresh,
+                      downsample,
+                      scale_x_y=1.,
+                      eps=1e-10):
+    an_num = len(anchors) // 2
+    x, y, w, h, obj, cls = _split_output(output, an_num, num_classes)
+    tx, ty, tw, th, tscale, tobj, tcls = _split_target(target)
+
+    tscale_tobj = tscale * tobj
+
+    scale_x_y = scale_x_y
+
+    if (abs(scale_x_y - 1.0) < eps):
+        loss_x = fluid.layers.sigmoid_cross_entropy_with_logits(
+            x, tx) * tscale_tobj
+        loss_x = fluid.layers.reduce_sum(loss_x, dim=[1, 2, 3])
+        loss_y = fluid.layers.sigmoid_cross_entropy_with_logits(
+            y, ty) * tscale_tobj
+        loss_y = fluid.layers.reduce_sum(loss_y, dim=[1, 2, 3])
+    else:
+        dx = scale_x_y * fluid.layers.sigmoid(x) - 0.5 * (scale_x_y - 1.0)
+        dy = scale_x_y * fluid.layers.sigmoid(y) - 0.5 * (scale_x_y - 1.0)
+        loss_x = fluid.layers.abs(dx - tx) * tscale_tobj
+        loss_x = fluid.layers.reduce_sum(loss_x, dim=[1, 2, 3])
+        loss_y = fluid.layers.abs(dy - ty) * tscale_tobj
+        loss_y = fluid.layers.reduce_sum(loss_y, dim=[1, 2, 3])
+
+    # NOTE: we refined loss function of (w, h) as L1Loss
+    loss_w = fluid.layers.abs(w - tw) * tscale_tobj
+    loss_w = fluid.layers.reduce_sum(loss_w, dim=[1, 2, 3])
+    loss_h = fluid.layers.abs(h - th) * tscale_tobj
+    loss_h = fluid.layers.reduce_sum(loss_h, dim=[1, 2, 3])
+
+    loss_obj_pos, loss_obj_neg = _calc_obj_loss(
+        output, obj, tobj, gt_box, batch_size, anchors, num_classes, downsample,
+        ignore_thresh, scale_x_y)
+
+    loss_cls = fluid.layers.sigmoid_cross_entropy_with_logits(cls, tcls)
+    loss_cls = fluid.layers.elementwise_mul(loss_cls, tobj, axis=0)
+    loss_cls = fluid.layers.reduce_sum(loss_cls, dim=[1, 2, 3, 4])
+
+    loss_xys = fluid.layers.reduce_mean(loss_x + loss_y)
+    loss_whs = fluid.layers.reduce_mean(loss_w + loss_h)
+    loss_objs = fluid.layers.reduce_mean(loss_obj_pos + loss_obj_neg)
+    loss_clss = fluid.layers.reduce_mean(loss_cls)
+
+    losses_all = {
+        "loss_xy": fluid.layers.sum(loss_xys),
+        "loss_wh": fluid.layers.sum(loss_whs),
+        "loss_loc": fluid.layers.sum(loss_xys) + fluid.layers.sum(loss_whs),
+        "loss_obj": fluid.layers.sum(loss_objs),
+        "loss_cls": fluid.layers.sum(loss_clss),
+    }
+    return losses_all, x, y, tx, ty
+
+
+def gt2yolotarget(gt_bbox, gt_class, gt_score, anchors, mask, num_classes, size,
+                  stride):
+    grid_h, grid_w = size
+    h, w = grid_h * stride, grid_w * stride
+    an_hw = np.array(anchors) / np.array([[w, h]])
+    target = np.zeros(
+        (len(mask), 6 + num_classes, grid_h, grid_w), dtype=np.float32)
+    for b in range(gt_bbox.shape[0]):
+        gx, gy, gw, gh = gt_bbox[b, :]
+        cls = gt_class[b]
+        score = gt_score[b]
+        if gw <= 0. or gh <= 0. or score <= 0.:
+            continue
+
+        # find best match anchor index
+        best_iou = 0.
+        best_idx = -1
+        for an_idx in range(an_hw.shape[0]):
+            iou = jaccard_overlap([0., 0., gw, gh],
+                                  [0., 0., an_hw[an_idx, 0], an_hw[an_idx, 1]])
+            if iou > best_iou:
+                best_iou = iou
+                best_idx = an_idx
+
+        gi = int(gx * grid_w)
+        gj = int(gy * grid_h)
+
+        # gtbox should be regresed in this layes if best match 
+        # anchor index in anchor mask of this layer
+        if best_idx in mask:
+            best_n = mask.index(best_idx)
+
+            # x, y, w, h, scale
+            target[best_n, 0, gj, gi] = gx * grid_w - gi
+            target[best_n, 1, gj, gi] = gy * grid_h - gj
+            target[best_n, 2, gj, gi] = np.log(gw * w / anchors[best_idx][0])
+            target[best_n, 3, gj, gi] = np.log(gh * h / anchors[best_idx][1])
+            target[best_n, 4, gj, gi] = 2.0 - gw * gh
+
+            # objectness record gt_score
+            # if target[best_n, 5, gj, gi] > 0:
+            #     print('find 1 duplicate')
+            target[best_n, 5, gj, gi] = score
+
+            # classification
+            target[best_n, 6 + cls, gj, gi] = 1.
+
+    return target
+
+
+class TestYolov3LossOp(unittest.TestCase):
+    def setUp(self):
+        self.initTestCase()
+        x = np.random.uniform(0, 1, self.x_shape).astype('float64')
+        gtbox = np.random.random(size=self.gtbox_shape).astype('float64')
+        gtlabel = np.random.randint(0, self.class_num, self.gtbox_shape[:2])
+        gtmask = np.random.randint(0, 2, self.gtbox_shape[:2])
+        gtbox = gtbox * gtmask[:, :, np.newaxis]
+        gtlabel = gtlabel * gtmask
+
+        gtscore = np.ones(self.gtbox_shape[:2]).astype('float64')
+        if self.gtscore:
+            gtscore = np.random.random(self.gtbox_shape[:2]).astype('float64')
+
+        target = []
+        for box, label, score in zip(gtbox, gtlabel, gtscore):
+            target.append(
+                gt2yolotarget(box, label, score, self.anchors, self.anchor_mask,
+                              self.class_num, (self.h, self.w
+                                               ), self.downsample_ratio))
+
+        self.target = np.array(target).astype('float64')
+
+        self.mask_anchors = []
+        for i in self.anchor_mask:
+            self.mask_anchors.extend(self.anchors[i])
+        self.x = x
+        self.gtbox = gtbox
+        self.gtlabel = gtlabel
+        self.gtscore = gtscore
+
+    def initTestCase(self):
+        self.b = 8
+        self.h = 19
+        self.w = 19
+        self.anchors = [[10, 13], [16, 30], [33, 23], [30, 61], [62, 45],
+                        [59, 119], [116, 90], [156, 198], [373, 326]]
+        self.anchor_mask = [6, 7, 8]
+        self.na = len(self.anchor_mask)
+        self.class_num = 80
+        self.ignore_thresh = 0.7
+        self.downsample_ratio = 32
+        self.x_shape = (self.b, len(self.anchor_mask) * (5 + self.class_num),
+                        self.h, self.w)
+        self.gtbox_shape = (self.b, 40, 4)
+        self.gtscore = True
+        self.use_label_smooth = False
+        self.scale_x_y = 1.
+
+    def test_loss(self):
+        x, gtbox, gtlabel, gtscore, target = self.x, self.gtbox, self.gtlabel, self.gtscore, self.target
+        yolo_loss = YOLOv3Loss(
+            ignore_thresh=self.ignore_thresh,
+            label_smooth=self.use_label_smooth,
+            num_classes=self.class_num,
+            downsample=self.downsample_ratio,
+            scale_x_y=self.scale_x_y)
+        x = paddle.to_tensor(x.astype(np.float32))
+        gtbox = paddle.to_tensor(gtbox.astype(np.float32))
+        gtlabel = paddle.to_tensor(gtlabel.astype(np.float32))
+        gtscore = paddle.to_tensor(gtscore.astype(np.float32))
+        t = paddle.to_tensor(target.astype(np.float32))
+        anchor = [self.anchors[i] for i in self.anchor_mask]
+        (yolo_loss1, px, py, tx, ty) = fine_grained_loss(
+            output=x,
+            target=t,
+            gt_box=gtbox,
+            batch_size=self.b,
+            num_classes=self.class_num,
+            anchors=self.mask_anchors,
+            ignore_thresh=self.ignore_thresh,
+            downsample=self.downsample_ratio,
+            scale_x_y=self.scale_x_y)
+        yolo_loss2 = yolo_loss.yolov3_loss(
+            x, t, gtbox, anchor, self.downsample_ratio, self.scale_x_y)
+        for k in yolo_loss2:
+            self.assertAlmostEqual(
+                yolo_loss1[k].numpy()[0],
+                yolo_loss2[k].numpy()[0],
+                delta=1e-2,
+                msg=k)
+
+
+class TestYolov3LossNoGTScore(TestYolov3LossOp):
+    def initTestCase(self):
+        self.b = 1
+        self.h = 76
+        self.w = 76
+        self.anchors = [[10, 13], [16, 30], [33, 23], [30, 61], [62, 45],
+                        [59, 119], [116, 90], [156, 198], [373, 326]]
+        self.anchor_mask = [0, 1, 2]
+        self.na = len(self.anchor_mask)
+        self.class_num = 80
+        self.ignore_thresh = 0.7
+        self.downsample_ratio = 8
+        self.x_shape = (self.b, len(self.anchor_mask) * (5 + self.class_num),
+                        self.h, self.w)
+        self.gtbox_shape = (self.b, 40, 4)
+        self.gtscore = False
+        self.use_label_smooth = False
+        self.scale_x_y = 1.
+
+
+class TestYolov3LossWithScaleXY(TestYolov3LossOp):
+    def initTestCase(self):
+        self.b = 5
+        self.h = 38
+        self.w = 38
+        self.anchors = [[10, 13], [16, 30], [33, 23], [30, 61], [62, 45],
+                        [59, 119], [116, 90], [156, 198], [373, 326]]
+        self.anchor_mask = [3, 4, 5]
+        self.na = len(self.anchor_mask)
+        self.class_num = 80
+        self.ignore_thresh = 0.7
+        self.downsample_ratio = 16
+        self.x_shape = (self.b, len(self.anchor_mask) * (5 + self.class_num),
+                        self.h, self.w)
+        self.gtbox_shape = (self.b, 40, 4)
+        self.gtscore = True
+        self.use_label_smooth = False
+        self.scale_x_y = 1.2
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/ppdet/modeling/utils/__init__.py b/ppdet/modeling/utils/__init__.py
new file mode 100644
index 0000000000000000000000000000000000000000..e27f26a6f1254241a760af2b41a7eb26eb463ad6
--- /dev/null
+++ b/ppdet/modeling/utils/__init__.py
@@ -0,0 +1,17 @@
+# Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from . import bbox_util
+
+from .bbox_util import *
diff --git a/ppdet/modeling/utils/bbox_util.py b/ppdet/modeling/utils/bbox_util.py
new file mode 100644
index 0000000000000000000000000000000000000000..9672ed484840b60f68bd8fc1b9b55a72b88a13ef
--- /dev/null
+++ b/ppdet/modeling/utils/bbox_util.py
@@ -0,0 +1,134 @@
+# Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import paddle
+import paddle.nn.functional as F
+import math
+
+
+def xywh2xyxy(box):
+    out = paddle.zeros_like(box)
+    out[:, :, 0:2] = box[:, :, 0:2] - box[:, :, 2:4] / 2
+    out[:, :, 2:4] = box[:, :, 0:2] + box[:, :, 2:4] / 2
+    return out
+
+
+def make_grid(h, w, dtype):
+    yv, xv = paddle.meshgrid([paddle.arange(h), paddle.arange(w)])
+    return paddle.stack((xv, yv), 2).cast(dtype=dtype)
+
+
+def decode_yolo(box, anchor, downsample_ratio):
+    """decode yolo box
+
+    Args:
+        box (Tensor): pred with the shape [b, h, w, na, 4]
+        anchor (list): anchor with the shape [na, 2]
+        downsample_ratio (int): downsample ratio, default 32
+        scale (float): scale, default 1.
+    
+    Return:
+        box (Tensor): decoded box, with the shape [b, h, w, na, 4]
+    """
+    h, w, na = box.shape[1:4]
+    grid = make_grid(h, w, box.dtype).reshape((1, h, w, 1, 2))
+    box[:, :, :, :, 0:2] = box[:, :, :, :, :2] + grid
+    box[:, :, :, :, 0] = box[:, :, :, :, 0] / w
+    box[:, :, :, :, 1] = box[:, :, :, :, 1] / h
+
+    anchor = paddle.to_tensor(anchor)
+    anchor = paddle.cast(anchor, box.dtype)
+    anchor = anchor.reshape((1, 1, 1, na, 2))
+    box[:, :, :, :, 2:4] = paddle.exp(box[:, :, :, :, 2:4]) * anchor
+    box[:, :, :, :, 2] = box[:, :, :, :, 2] / (downsample_ratio * w)
+    box[:, :, :, :, 3] = box[:, :, :, :, 3] / (downsample_ratio * h)
+    return box
+
+
+def iou_similarity(box1, box2, eps=1e-9):
+    """Calculate iou of box1 and box2
+
+    Args:
+        box1 (Tensor): box with the shape [N, M1, 4]
+        box2 (Tensor): box with the shape [N, M2, 4]
+    
+    Return:
+        iou (Tensor): iou between box1 and box2 with the shape [N, M1, M2]
+    """
+    box1 = box1.unsqueeze(2)  # [N, M1, 4] -> [N, M1, 1, 4]
+    box2 = box2.unsqueeze(1)  # [N, M2, 4] -> [N, 1, M2, 4]
+    px1y1, px2y2 = box1[:, :, :, 0:2], box1[:, :, :, 2:4]
+    gx1y1, gx2y2 = box2[:, :, :, 0:2], box2[:, :, :, 2:4]
+    x1y1 = paddle.maximum(px1y1, gx1y1)
+    x2y2 = paddle.minimum(px2y2, gx2y2)
+    overlap = (x2y2 - x1y1).clip(0).prod(-1)
+    area1 = (px2y2 - px1y1).clip(0).prod(-1)
+    area2 = (gx2y2 - gx1y1).clip(0).prod(-1)
+    union = area1 + area2 - overlap + eps
+    return overlap / union
+
+
+def bbox_iou(box1, box2, giou=False, diou=False, ciou=False, eps=1e-9):
+    """calculate the iou of box1 and box2
+
+    Args:
+        box1 (Tensor): box1 with the shape (N, M, 4)
+        box2 (Tensor): box1 with the shape (N, M, 4)
+        giou (bool): whether use giou or not, default False
+        diou (bool): whether use diou or not, default False
+        ciou (bool): whether use ciou or not, default False
+        eps (float): epsilon to avoid divide by zero
+
+    Return:
+        iou (Tensor): iou of box1 and box1, with the shape (N, M)
+    """
+    px1y1, px2y2 = box1[:, :, 0:2], box1[:, :, 2:4]
+    gx1y1, gx2y2 = box2[:, :, 0:2], box2[:, :, 2:4]
+    x1y1 = paddle.maximum(px1y1, gx1y1)
+    x2y2 = paddle.minimum(px2y2, gx2y2)
+
+    overlap = (x2y2 - x1y1).clip(0).prod(-1)
+    area1 = (px2y2 - px1y1).clip(0).prod(-1)
+    area2 = (gx2y2 - gx1y1).clip(0).prod(-1)
+    union = area1 + area2 - overlap + eps
+    iou = overlap / union
+    if giou or ciou or diou:
+        # convex w, h
+        cwh = paddle.maximum(px2y2, gx2y2) - paddle.minimum(px1y1, gx1y1)
+        if ciou or diou:
+            # convex diagonal squared
+            c2 = (cwh**2).sum(2) + eps
+            # center distance
+            rho2 = ((px1y1 + px2y2 - gx1y1 - gx2y2)**2).sum(2) / 4
+            if diou:
+                return iou - rho2 / c2
+            elif ciou:
+                wh1 = px2y2 - px1y1
+                wh2 = gx2y2 - gx1y1
+                w1, h1 = wh1[:, :, 0], wh1[:, :, 1] + eps
+                w2, h2 = wh2[:, :, 0], wh2[:, :, 1] + eps
+                v = (4 / math.pi**2) * paddle.pow(
+                    paddle.atan(w1 / h1) - paddle.atan(w2 / h2), 2)
+                alpha = v / (1 + eps - iou + v)
+                alpha.stop_gradient = True
+                return iou - (rho2 / c2 + v * alpha)
+        else:
+            c_area = cwh.prod(2) + eps
+            return iou - (c_area - union) / c_area
+    else:
+        return iou
diff --git a/tools/train.py b/tools/train.py
index a59dd192d305ccfee320272e6363d32fc13b27ac..318ae855fb2dfb0338f39e53f08c71608137d132 100755
--- a/tools/train.py
+++ b/tools/train.py
@@ -30,7 +30,6 @@ import datetime
 import numpy as np
 from collections import deque
 import paddle
-from paddle import fluid
 from ppdet.core.workspace import load_config, merge_config, create
 from ppdet.utils.stats import TrainingStats
 from ppdet.utils.check import check_gpu, check_version, check_config
@@ -122,7 +121,6 @@ def run(FLAGS, cfg, place):
         dataset, cfg['worker_num'], place)
 
     # Model
-    main_arch = cfg.architecture
     model = create(cfg.architecture)
 
     # Optimizer
@@ -137,19 +135,28 @@ def run(FLAGS, cfg, place):
                              cfg.get('load_static_weights', False),
                              FLAGS.weight_type)
 
+    if getattr(model.backbone, 'norm_type', None) == 'sync_bn':
+        assert cfg.use_gpu and ParallelEnv(
+        ).nranks > 1, 'you should use bn rather than sync_bn while using a single gpu'
+    # sync_bn = (getattr(model.backbone, 'norm_type', None) == 'sync_bn' and
+    #            cfg.use_gpu and ParallelEnv().nranks > 1)
+    # if sync_bn:
+    #     model = paddle.nn.SyncBatchNorm.convert_sync_batchnorm(model)
+
     # Parallel Model 
     if ParallelEnv().nranks > 1:
         model = paddle.DataParallel(model)
 
+    fields = train_loader.collate_fn.output_fields
     # Run Train
-    start_iter = 0
     time_stat = deque(maxlen=cfg.log_iter)
     start_time = time.time()
     end_time = time.time()
     # Run Train
     start_epoch = optimizer.state_dict()['LR_Scheduler']['last_epoch']
-    for e_id in range(int(cfg.epoch)):
-        cur_eid = e_id + start_epoch
+    for epoch_id in range(int(cfg.epoch)):
+        cur_eid = epoch_id + start_epoch
+        train_loader.dataset.epoch = epoch_id
         for iter_id, data in enumerate(train_loader):
             start_time = end_time
             end_time = time.time()
@@ -161,8 +168,7 @@ def run(FLAGS, cfg, place):
 
             # Model Forward
             model.train()
-            outputs = model(data, cfg['TrainReader']['inputs_def']['fields'],
-                            'train')
+            outputs = model(data, fields, 'train')
 
             # Model Backward
             loss = outputs['loss']
@@ -179,7 +185,7 @@ def run(FLAGS, cfg, place):
 
             if ParallelEnv().nranks < 2 or ParallelEnv().local_rank == 0:
                 # Log state 
-                if e_id == 0 and iter_id == 0:
+                if epoch_id == 0 and iter_id == 0:
                     train_stats = TrainingStats(cfg.log_iter, outputs.keys())
                 train_stats.update(outputs)
                 logs = train_stats.log()