diff --git a/python/sglang/bench_offline_throughput.py b/python/sglang/bench_offline_throughput.py
index a3793f921..7717c16f0 100644
--- a/python/sglang/bench_offline_throughput.py
+++ b/python/sglang/bench_offline_throughput.py
@@ -23,7 +23,7 @@ import json
 import logging
 import random
 import time
-from typing import List, Optional, Tuple
+from typing import Dict, List, Optional, Tuple
 
 import numpy as np
 
@@ -55,6 +55,7 @@ class BenchArgs:
     gen_question_len: int = 128
     gen_output_len: int = 256
     disable_ignore_eos: bool = False
+    extra_request_body: Optional[str] = None
     seed: int = 1
     do_not_exit: bool = False
 
@@ -143,6 +144,13 @@ class BenchArgs:
             default=BenchArgs.disable_ignore_eos,
             help="Disable ignore EOS token",
         )
+        parser.add_argument(
+            "--extra-request-body",
+            metavar='{"key1": "value1", "key2": "value2"}',
+            type=str,
+            help="Append given JSON object to the request payload. You can use this to specify"
+            "additional generate params like sampling params.",
+        )
         parser.add_argument("--seed", type=int, default=1, help="The random seed.")
         parser.add_argument(
             "--do-not-exit",
@@ -161,6 +169,7 @@ def throughput_test_once(
     backend,
     reqs: List[Tuple[str, int, int]],
     ignore_eos: bool,
+    extra_request_body: Dict,
 ):
     measurement_results = {
         "backend": backend_name,
@@ -180,6 +189,7 @@ def throughput_test_once(
             "temperature": 0,
             "max_new_tokens": r[2],
             "ignore_eos": ignore_eos,
+            **extra_request_body,
         }
         for r in reqs
     ]
@@ -233,6 +243,11 @@ def throughput_test(
     random.seed(bench_args.seed)
     np.random.seed(bench_args.seed)
 
+    # Parse args
+    extra_request_body = {}
+    if bench_args.extra_request_body:
+        extra_request_body = json.loads(args.extra_request_body)
+
     # Read dataset
     input_requests = get_dataset(bench_args, tokenizer)
 
@@ -252,6 +267,7 @@ def throughput_test(
         backend=backend,
         reqs=warmup_requests,
         ignore_eos=not bench_args.disable_ignore_eos,
+        extra_request_body=extra_request_body,
     )
 
     logging.info("\nBenchmark...")
@@ -260,6 +276,7 @@ def throughput_test(
         backend=backend,
         reqs=input_requests,
         ignore_eos=not bench_args.disable_ignore_eos,
+        extra_request_body=extra_request_body,
     )
 
     if bench_args.result_filename: