diff --git a/paddle/fluid/operators/p_norm_op.cc b/paddle/fluid/operators/p_norm_op.cc
index cd7a8c6d24eaaca096b630b74dd7cd1bb9d35d09..426a059c2aea1dfb2f17ebf4dbe6ff9a9f13b10a 100644
--- a/paddle/fluid/operators/p_norm_op.cc
+++ b/paddle/fluid/operators/p_norm_op.cc
@@ -116,6 +116,9 @@ class PnormOp : public framework::OperatorWithKernel {
       for (int i = 0; i < x_dim.size(); ++i) {
         if (i != axis) reduce_dims.emplace_back(x_dim[i]);
       }
+      if (reduce_dims.size() == 0) {
+        reduce_dims.emplace_back(1);
+      }
     }
     x_dim[axis] = 1;