diff --git a/configs/ppyolo/_base_/optimizer_1x.yml b/configs/ppyolo/_base_/optimizer_1x.yml
index 8e6301e32f21e1b2f49fc5eb36427c9c1acbec79..fe51b296c72e4c663bf4c611d80a1173ff69f6a9 100644
--- a/configs/ppyolo/_base_/optimizer_1x.yml
+++ b/configs/ppyolo/_base_/optimizer_1x.yml
@@ -13,6 +13,7 @@ LearningRate:
     steps: 4000
 
 OptimizerBuilder:
+  clip_grad_by_norm: 35.
   optimizer:
     momentum: 0.9
     type: Momentum
diff --git a/configs/ppyolo/_base_/optimizer_2x.yml b/configs/ppyolo/_base_/optimizer_2x.yml
index 92ddbf2a713595dfcd48a748ac77186fe9312132..c601a18601c7a0d8a79049cb0d1b9a87f41900f4 100644
--- a/configs/ppyolo/_base_/optimizer_2x.yml
+++ b/configs/ppyolo/_base_/optimizer_2x.yml
@@ -13,6 +13,7 @@ LearningRate:
     steps: 4000
 
 OptimizerBuilder:
+  clip_grad_by_norm: 35.
   optimizer:
     momentum: 0.9
     type: Momentum