diff --git a/deepmd/pt/train/training.py b/deepmd/pt/train/training.py
index 49eccd60dc..392bdb8a7a 100644
--- a/deepmd/pt/train/training.py
+++ b/deepmd/pt/train/training.py
@@ -689,7 +689,7 @@ def step(_step_id, task_key="Default") -> None:
                 )
                 loss.backward()
                 if self.gradient_max_norm > 0.0:
-                    grad_norm = torch.nn.utils.clip_grad_norm_(
+                    torch.nn.utils.clip_grad_norm_(
                         self.wrapper.parameters(),
                         self.gradient_max_norm,
                         error_if_nonfinite=True,