diff --git a/onnxruntime/python/tools/transformers/gpt2_beamsearch_helper.py b/onnxruntime/python/tools/transformers/gpt2_beamsearch_helper.py
index a3fa8ec875..0001785a1c 100644
--- a/onnxruntime/python/tools/transformers/gpt2_beamsearch_helper.py
+++ b/onnxruntime/python/tools/transformers/gpt2_beamsearch_helper.py
@@ -610,6 +610,18 @@ class Gpt2BeamSearchHelper(Gpt2Helper):
         input_names.append("prev_step_scores")
         input_names.extend(past_names)
 
+        # add dynamic output axes
+        present_axes = {1: 'batch_size', 3: 'cur_seq_len'}
+        dynamic_axes["last_state"] =  {0: 'batch_size', 1: 'beam_size'}
+        for i in range(num_layer):
+            dynamic_axes["present_" + str(i)] = present_axes
+
+        dynamic_axes["output_selected_indices"] = {0: "batch_size", 1: "'beam_size_or_1'"}
+        dynamic_axes["output_log_probs"] =  {0: "batch_size", 1: "'beam_size'"}
+        dynamic_axes["output_unfinished_sents"] =  {0: "batch_size", 1: "'beam_size'"}
+        dynamic_axes["current_step_results"] = {0: "beam_size_or_1", 1: "total_seq_len"}
+        dynamic_axes["current_step_scores"] = {0: "beam_size_or_1", 1: "total_seq_len"}
+
         logger.info(
             f"Shapes: input_ids={dummy_inputs.input_ids.shape} past={dummy_inputs.past[0].shape} output={outputs[0].shape} present={outputs[1][0].shape}"
         )