diff --git a/ppdet/modeling/heads/centernet_head.py b/ppdet/modeling/heads/centernet_head.py
index aa3fbe2c318cdfe3ded000897675103b6e664dcd..49c7b0df10e444459f3f4e72768efe7841ccead0 100755
--- a/ppdet/modeling/heads/centernet_head.py
+++ b/ppdet/modeling/heads/centernet_head.py
@@ -98,7 +98,8 @@ class CenterNetHead(nn.Layer):
                 stride=1,
                 padding=0,
                 bias=True))
-        self.heatmap[2].conv.bias[:] = -2.19
+        with paddle.no_grad():
+            self.heatmap[2].conv.bias[:] = -2.19
         self.size = nn.Sequential(
             ConvLayer(
                 in_channels, head_planes, kernel_size=3, padding=1, bias=True),