diff --git a/gateway/platforms/wecom.py b/gateway/platforms/wecom.py
index 873284de79..c93a8fe3d6 100644
--- a/gateway/platforms/wecom.py
+++ b/gateway/platforms/wecom.py
@@ -1015,6 +1015,8 @@ class WeComAdapter(BasePlatformAdapter):
         if not aes_key:
             raise ValueError("aes_key is required")
 
+        # WeCom doesn't pad base64 keys; add padding if needed
+        aes_key = aes_key + '=' * ((4 - len(aes_key) % 4) % 4)
         key = base64.b64decode(aes_key)
         if len(key) != 32:
             raise ValueError(f"Invalid WeCom AES key length: expected 32 bytes, got {len(key)}")