diff --git a/paddle/fluid/operators/math/concat.cu b/paddle/fluid/operators/math/concat.cu
index 6205f3cd85c7201e923eacad4319e2c6fda689fe..5863d74fca21de8b77bc208fb95d8fd52562f7a7 100644
--- a/paddle/fluid/operators/math/concat.cu
+++ b/paddle/fluid/operators/math/concat.cu
@@ -209,7 +209,7 @@ class ConcatGradFunctor<platform::CUDADeviceContext, T> {
 
     outputs_cols[0] = 0;
     for (int i = 0; i < o_num; ++i) {
-      int t_col = outputs->at(i)->numel() / out_row;
+      int t_col = ref_inputs.at(i)->numel() / out_row;
       if (sameShape) {
         if (t_col != out0_col) sameShape = false;
       }