diff --git a/paddle/phi/kernels/gpu/index_select_grad_kernel.cu b/paddle/phi/kernels/gpu/index_select_grad_kernel.cu
index 2fce40dbe7306a127ec9435bf0c4ca5c8d40e0b9..64e3428cc9aaf82e624dfc90d699c5db990612eb 100644
--- a/paddle/phi/kernels/gpu/index_select_grad_kernel.cu
+++ b/paddle/phi/kernels/gpu/index_select_grad_kernel.cu
@@ -87,7 +87,7 @@ void IndexSelectGradKernel(const Context& ctx,
   auto stream = ctx.stream();
 
   unsigned int block_dim = PADDLE_CUDA_NUM_THREADS;
-  dim3 grid_dim = dim3((numel + block_dim - 1) / block_dim);
+  dim3 grid_dim = dim3((out_nums + block_dim - 1) / block_dim);
   phi::backends::gpu::LimitGridDim(ctx, &grid_dim);
 
   phi::funcs::SetConstant<phi::GPUContext, T> index_select_grad_init;