diff --git a/ppocr/postprocess/db_postprocess.py b/ppocr/postprocess/db_postprocess.py
index d9c9869dfcd35cb9b491db826f3bff5f766723f4..c118a378b7dcd87a3d18a18f97de1a8ba175c3d0 100755
--- a/ppocr/postprocess/db_postprocess.py
+++ b/ppocr/postprocess/db_postprocess.py
@@ -11,7 +11,10 @@
 # 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.
-
+"""
+This code is refer from:
+https://github.com/WenmuZhou/DBNet.pytorch/blob/master/post_processing/seg_detector_representer.py
+"""
 from __future__ import absolute_import
 from __future__ import division
 from __future__ import print_function
@@ -190,7 +193,8 @@ class DBPostProcess(object):
 
 
 class DistillationDBPostProcess(object):
-    def __init__(self, model_name=["student"],
+    def __init__(self,
+                 model_name=["student"],
                  key=None,
                  thresh=0.3,
                  box_thresh=0.6,
@@ -201,12 +205,13 @@ class DistillationDBPostProcess(object):
                  **kwargs):
         self.model_name = model_name
         self.key = key
-        self.post_process = DBPostProcess(thresh=thresh,
-                 box_thresh=box_thresh,
-                 max_candidates=max_candidates,
-                 unclip_ratio=unclip_ratio,
-                 use_dilation=use_dilation,
-                 score_mode=score_mode)
+        self.post_process = DBPostProcess(
+            thresh=thresh,
+            box_thresh=box_thresh,
+            max_candidates=max_candidates,
+            unclip_ratio=unclip_ratio,
+            use_dilation=use_dilation,
+            score_mode=score_mode)
 
     def __call__(self, predicts, shape_list):
         results = {}