diff --git a/python/paddle/utils/image_util.py b/python/paddle/utils/image_util.py
index a8092349cde8a4cb30873bf819fd5ed96289a945..94029cff9fb5095b568a5facc4c6ff6fec3af4f3 100644
--- a/python/paddle/utils/image_util.py
+++ b/python/paddle/utils/image_util.py
@@ -34,7 +34,7 @@ def flip(im):
     """
     Return the flipped image.
     Flip an image along the horizontal direction.
-    im: input image, (H x W x K) ndarrays
+    im: input image, (K x H x W) ndarrays
     """
     if len(im.shape) == 3:
         return im[:, :, ::-1]