diff --git a/paddle/fluid/operators/sampling_id_op.h b/paddle/fluid/operators/sampling_id_op.h
index 14abb78e043890fe9f57f218d85cf8ca6098d302..133d3f72dbd6ab13c98d124369038309c94cba5b 100644
--- a/paddle/fluid/operators/sampling_id_op.h
+++ b/paddle/fluid/operators/sampling_id_op.h
@@ -54,7 +54,7 @@ class SamplingIdKernel : public framework::OpKernel<T> {
         static_cast<T>(context.Attr<float>("max")));
 
     std::vector<int64_t> ids(batch_size);
-    for (size_t i = 0; i < batch_size; ++i) {
+    for (int i = 0; i < batch_size; ++i) {
       T r = dist(engine);
       int idx = width - 1;
       for (int j = 0; j < width; ++j) {