diff --git a/python/sglang/srt/model_executor/expert_location_updater.py b/python/sglang/srt/model_executor/expert_location_updater.py
index 75fd7c2d7..5dce3d9a3 100644
--- a/python/sglang/srt/model_executor/expert_location_updater.py
+++ b/python/sglang/srt/model_executor/expert_location_updater.py
@@ -30,6 +30,9 @@ from sglang.srt.utils import get_bool_env_var
 logger = logging.getLogger(__name__)
 
 
+_LOG_INPUT = get_bool_env_var("SGLANG_EXPERT_LOCATION_UPDATER_LOG_INPUT")
+
+
 class ExpertLocationUpdater:
     def __init__(self):
         self._first_execution = True
@@ -175,6 +178,19 @@ def update_expert_weights_single_layer(
     assert isinstance(old_physical_to_logical_map, list)
     assert isinstance(new_physical_to_logical_map, list)
 
+    if _LOG_INPUT:
+        logger.info(
+            "update_expert_weights_single_layer "
+            f"{[x.shape for x in routed_experts_weights]=} "
+            f"{[x.shape for x in temp_buffers]=} "
+            f"{old_physical_to_logical_map=} "
+            f"{new_physical_to_logical_map=} "
+            f"{num_local_physical_experts=} "
+            f"{num_gpu_per_node=} "
+            f"{rank=} "
+            f"{world_size=} "
+        )
+
     output_logs = [] if debug else None
 
     num_physical_experts = len(old_physical_to_logical_map)