diff --git a/python/paddle/fluid/framework.py b/python/paddle/fluid/framework.py
index 9a69138591697e2a0961c34ad31f1b2025993b2e..67bb290ccdda8330171e3964aab9b9dc150c5746 100644
--- a/python/paddle/fluid/framework.py
+++ b/python/paddle/fluid/framework.py
@@ -763,6 +763,7 @@ class Block(object):
             raise ValueError("unsupported var type: %s", type(v))
 
         self.desc.rename_var(name, new_name)
+        # NOTE: v is destroyed by C++ after calling rename_var.
         d = self.desc.find_var(new_name)
         if var_type == "Parameter":
             var = Parameter(