diff --git a/paddle/fluid/API.spec b/paddle/fluid/API.spec
index c8e2da9b6ee32424920017e5cad8724dc5cb2099..aa373efdaea524f3fad03c3107404d0062ef4c0e 100644
--- a/paddle/fluid/API.spec
+++ b/paddle/fluid/API.spec
@@ -327,7 +327,7 @@ paddle.fluid.layers.generate_mask_labels (ArgSpec(args=['im_info', 'gt_classes',
 paddle.fluid.layers.iou_similarity (ArgSpec(args=['x', 'y', 'name'], varargs=None, keywords=None, defaults=(None,)), ('document', '587845f60c5d97ffdf2dfd21da52eca1'))
 paddle.fluid.layers.box_coder (ArgSpec(args=['prior_box', 'prior_box_var', 'target_box', 'code_type', 'box_normalized', 'name', 'axis'], varargs=None, keywords=None, defaults=('encode_center_size', True, None, 0)), ('document', '032d0f4b7d8f6235ee5d91e473344f0e'))
 paddle.fluid.layers.polygon_box_transform (ArgSpec(args=['input', 'name'], varargs=None, keywords=None, defaults=(None,)), ('document', '0e5ac2507723a0b5adec473f9556799b'))
-paddle.fluid.layers.yolov3_loss (ArgSpec(args=['x', 'gtbox', 'gtlabel', 'anchors', 'anchor_mask', 'class_num', 'ignore_thresh', 'downsample_ratio', 'name', 'gtscore', 'use_label_smooth'], varargs=None, keywords=None, defaults=(None, None, True)), ('document', '3a76e87a6d7b961612094d7b67cd8b2a'))
+paddle.fluid.layers.yolov3_loss (ArgSpec(args=['x', 'gtbox', 'gtlabel', 'anchors', 'anchor_mask', 'class_num', 'ignore_thresh', 'downsample_ratio', 'name', 'gtscore', 'use_label_smooth'], varargs=None, keywords=None, defaults=(None, None, True)), ('document', '3da31ac0f0c102b15f613bdaa2c2f7ac'))
 paddle.fluid.layers.box_clip (ArgSpec(args=['input', 'im_info', 'name'], varargs=None, keywords=None, defaults=(None,)), ('document', '397e9e02b451d99c56e20f268fa03f2e'))
 paddle.fluid.layers.multiclass_nms (ArgSpec(args=['bboxes', 'scores', 'score_threshold', 'nms_top_k', 'keep_top_k', 'nms_threshold', 'normalized', 'nms_eta', 'background_label', 'name'], varargs=None, keywords=None, defaults=(0.3, True, 1.0, 0, None)), ('document', 'ca7d1107b6c5d2d6d8221039a220fde0'))
 paddle.fluid.layers.distribute_fpn_proposals (ArgSpec(args=['fpn_rois', 'min_level', 'max_level', 'refer_level', 'refer_scale', 'name'], varargs=None, keywords=None, defaults=(None,)), ('document', '7bb011ec26bace2bc23235aa4a17647d'))
diff --git a/paddle/fluid/operators/detection/yolov3_loss_op.cc b/paddle/fluid/operators/detection/yolov3_loss_op.cc
index 27d8bb01325f90fbd23191bf5c45de4695aa8746..6c37da17f4011d38efcdc5406331f1be173dd0dd 100644
--- a/paddle/fluid/operators/detection/yolov3_loss_op.cc
+++ b/paddle/fluid/operators/detection/yolov3_loss_op.cc
@@ -162,7 +162,8 @@ class Yolov3LossOpMaker : public framework::OpProtoAndCheckerMaker {
     AddAttr<float>("ignore_thresh",
                    "The ignore threshold to ignore confidence loss.")
         .SetDefault(0.7);
-    AddAttr<bool>("use_label_smooth", "bool,default True", "use label smooth")
+    AddAttr<bool>("use_label_smooth",
+                  "Whether to use label smooth. Default True.")
         .SetDefault(true);
     AddComment(R"DOC(
          This operator generates yolov3 loss based on given predict result and ground
diff --git a/python/paddle/fluid/layers/detection.py b/python/paddle/fluid/layers/detection.py
index 1ecb9b9e344d07fc19f827912567e04bd1545812..4cc10182eafbe889da6d4f39ca764535a753b5a5 100644
--- a/python/paddle/fluid/layers/detection.py
+++ b/python/paddle/fluid/layers/detection.py
@@ -535,9 +535,9 @@ def yolov3_loss(x,
         class_num (int): ${class_num_comment}
         ignore_thresh (float): ${ignore_thresh_comment}
         downsample_ratio (int): ${downsample_ratio_comment}
-        name (string): the name of yolov3 loss
+        name (string): the name of yolov3 loss. Default None.
         gtscore (Variable): mixup score of ground truth boxes, shoud be in shape
-                            of [N, B].
+                            of [N, B]. Default None.
         use_label_smooth (bool): ${use_label_smooth_comment}
 
     Returns: