diff --git a/requirements.txt b/requirements.txt
index 1a6f9dd0c..e64afd1ee 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -8,7 +8,10 @@ pypinyin==0.50.0
 tensorboard
 typeguard
 dill
-black==22.3.0
-isort==5.10.1
 onnx==1.15.0
 onnxruntime==1.16.3
+
+# style check session:
+black==22.3.0
+isort==5.10.1
+flake8==5.0.4 
\ No newline at end of file