diff --git a/ppocr/metrics/kie_metric.py b/ppocr/metrics/kie_metric.py
index 761965cfcc25d2a6de30342769d01b36d6212d98..f3bce0411d6521b1756892cbd7b4c6fcb7bcfb6c 100644
--- a/ppocr/metrics/kie_metric.py
+++ b/ppocr/metrics/kie_metric.py
@@ -11,6 +11,7 @@
 # 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.
+# The code is refer from: https://github.com/open-mmlab/mmocr/blob/main/mmocr/core/evaluation/kie_metric.py
 
 from __future__ import absolute_import
 from __future__ import division