diff --git a/imperative/python/megengine/functional/nn.py b/imperative/python/megengine/functional/nn.py
index b87ded3ed6094365e92e59146eb6bfbd33f39240..72078a7b5d65666fbe12139d4524f4c4a61bd0bb 100644
--- a/imperative/python/megengine/functional/nn.py
+++ b/imperative/python/megengine/functional/nn.py
@@ -1304,6 +1304,8 @@ def dropout(inp: Tensor, drop_prob: float, training: bool = True) -> Tensor:
 
     """
     assert 0 <= drop_prob < 1
+    if drop_prob == 0:
+        return inp
     rv = uniform(size=inp.shape)
     mask = rv > drop_prob
     inp *= mask.astype(inp.dtype)