diff --git a/python/llm/dev/benchmark/perplexity/run_longbench.py b/python/llm/dev/benchmark/perplexity/run_longbench.py
index 92b4999a..c250d35f 100644
--- a/python/llm/dev/benchmark/perplexity/run_longbench.py
+++ b/python/llm/dev/benchmark/perplexity/run_longbench.py
@@ -37,6 +37,7 @@ def get_arguments():
     parser.add_argument("--dataset_path", required=False, type=str, default=None)
     parser.add_argument("--language", required=False, type=str, default="en", choices=['en', 'zh', 'all'])
     parser.add_argument("--precisions", required=False, type=str, default=None, nargs='+')
+    parser.add_argument("--mixed_precision", action="store_true") 
     parser.add_argument("--device", type=str, default="xpu")
     parser.add_argument("--output_path", default=None)
     return parser.parse_args()
@@ -95,11 +96,11 @@ def main():
         log_dir = f"{output_path}/{model_name}/{args.device}/{precision}/{args.language}"
         os.makedirs(log_dir, exist_ok=True)
         results = {}
-        ppl_evaluator = BigDLPPL(model_path=args.model_path, device=args.device, **model_kwargs)
+        ppl_evaluator = BigDLPPL(model_path=args.model_path, device=args.device, mixed_precision=args.mixed_precision, **model_kwargs)
         ppl = ppl_evaluator.perplexity_hf(encoded_texts)
         summary[precision] = ppl
         results['results'] = ppl
-        results['config'] = {"model": model_name, "precision": precision, "device": args.device, "seq_len": args.seq_len, "language": args.language}
+        results['config'] = {"model": model_name, "precision": precision, "mixed_precision": args.mixed_precision, "device": args.device, "seq_len": args.seq_len, "language": args.language }
         dumped = json.dumps(results, indent=2)
         print(dumped)