diff --git a/python/paddle/fluid/transpiler/memory_optimization_transpiler.py b/python/paddle/fluid/transpiler/memory_optimization_transpiler.py
index 861bb5fae5d7a8561ded1f547fbb86ae1e1a073e..7298bfe16ef7232ba072aaa3cf426914a1f5d8a2 100755
--- a/python/paddle/fluid/transpiler/memory_optimization_transpiler.py
+++ b/python/paddle/fluid/transpiler/memory_optimization_transpiler.py
@@ -171,7 +171,7 @@ class ControlFlowGraph(object):
                 self._live_out[i] |= self._live_in[s]
             self._live_in[i] = self._uses[i] | (
                 self._live_out[i] - self._defs[i])
-            if live_in[i] != self._live_in[i]:
+            if live_in[i] != set(self._live_in[i]):
                 for d in self._presuccessors[i]:
                     worklist.append(d)