diff --git a/imperative/python/megengine/distributed/functional.py b/imperative/python/megengine/distributed/functional.py
index 9171b64e..f0650b6f 100644
--- a/imperative/python/megengine/distributed/functional.py
+++ b/imperative/python/megengine/distributed/functional.py
@@ -271,6 +271,7 @@ def all_reduce_max(
     :param inp: input tensor.
     :param group: communication group.
     :param device: execution device.
+    :returns: reduced tensor. 
     """
     mode = CollectiveComm.Mode.ALL_REDUCE_MAX
     return collective_comm(inp, mode, group, device)