diff --git a/ppdet/data/source/keypoint_coco.py b/ppdet/data/source/keypoint_coco.py
index 5b7b99ee9a20517a8deebfcc0730720c18fcf138..fdea57adac70210ea68dd3ab49217fe4547be00a 100644
--- a/ppdet/data/source/keypoint_coco.py
+++ b/ppdet/data/source/keypoint_coco.py
@@ -63,6 +63,9 @@ class KeypointBottomUpBaseDataset(DetDataset):
         self.ann_info['num_joints'] = num_joints
         self.img_ids = []
 
+    def parse_dataset(self):
+        pass
+
     def __len__(self):
         """Get dataset length."""
         return len(self.img_ids)
@@ -136,26 +139,30 @@ class KeypointBottomUpCocoDataset(KeypointBottomUpBaseDataset):
         super().__init__(dataset_dir, image_dir, anno_path, num_joints,
                          transform, shard, test_mode)
 
-        ann_file = os.path.join(dataset_dir, anno_path)
-        self.coco = COCO(ann_file)
+        self.ann_file = os.path.join(dataset_dir, anno_path)
+        self.shard = shard
+        self.test_mode = test_mode
+
+    def parse_dataset(self):
+        self.coco = COCO(self.ann_file)
 
         self.img_ids = self.coco.getImgIds()
-        if not test_mode:
+        if not self.test_mode:
             self.img_ids = [
                 img_id for img_id in self.img_ids
                 if len(self.coco.getAnnIds(
                     imgIds=img_id, iscrowd=None)) > 0
             ]
-        blocknum = int(len(self.img_ids) / shard[1])
-        self.img_ids = self.img_ids[(blocknum * shard[0]):(blocknum * (shard[0]
-                                                                       + 1))]
+        blocknum = int(len(self.img_ids) / self.shard[1])
+        self.img_ids = self.img_ids[(blocknum * self.shard[0]):(blocknum * (
+            self.shard[0] + 1))]
         self.num_images = len(self.img_ids)
         self.id2name, self.name2id = self._get_mapping_id_name(self.coco.imgs)
         self.dataset_name = 'coco'
 
         cat_ids = self.coco.getCatIds()
         self.catid2clsid = dict({catid: i for i, catid in enumerate(cat_ids)})
-        print(f'=> num_images: {self.num_images}')
+        print('=> num_images: {}'.format(self.num_images))
 
     @staticmethod
     def _get_mapping_id_name(imgs):
@@ -301,20 +308,23 @@ class KeypointBottomUpCrowdPoseDataset(KeypointBottomUpCocoDataset):
         super().__init__(dataset_dir, image_dir, anno_path, num_joints,
                          transform, shard, test_mode)
 
-        ann_file = os.path.join(dataset_dir, anno_path)
+        self.ann_file = os.path.join(dataset_dir, anno_path)
+        self.shard = shard
+        self.test_mode = test_mode
 
-        self.coco = COCO(ann_file)
+    def parse_dataset(self):
+        self.coco = COCO(self.ann_file)
 
         self.img_ids = self.coco.getImgIds()
-        if not test_mode:
+        if not self.test_mode:
             self.img_ids = [
                 img_id for img_id in self.img_ids
                 if len(self.coco.getAnnIds(
                     imgIds=img_id, iscrowd=None)) > 0
             ]
-        blocknum = int(len(self.img_ids) / shard[1])
-        self.img_ids = self.img_ids[(blocknum * shard[0]):(blocknum * (shard[0]
-                                                                       + 1))]
+        blocknum = int(len(self.img_ids) / self.shard[1])
+        self.img_ids = self.img_ids[(blocknum * self.shard[0]):(blocknum * (
+            self.shard[0] + 1))]
         self.num_images = len(self.img_ids)
         self.id2name, self.name2id = self._get_mapping_id_name(self.coco.imgs)