diff --git a/swift/rlhf_trainers/rollout_mixin.py b/swift/rlhf_trainers/rollout_mixin.py
index f4ea58e1d0..2d968a5bee 100644
--- a/swift/rlhf_trainers/rollout_mixin.py
+++ b/swift/rlhf_trainers/rollout_mixin.py
@@ -34,7 +34,7 @@
 from swift.template import Template
 from swift.tuners import Swift
 from swift.utils import (get_current_device, get_logger, is_deepspeed_enabled, is_vllm_available, remove_response,
-                         to_device)
+                         synchronize, to_device)
 from .arguments import RolloutTrainerArgumentsMixin
 from .rlhf_mixin import RLHFTrainerMixin
 from .utils import (VLLM_LORA_INT_ID, VLLM_LORA_NAME, VLLM_LORA_PATH, FlattenedTensorBucket, TensorLoRARequest,
@@ -570,6 +570,8 @@ def _load_state_dict_to_vllm(self, state_dict):
             # Patch MoE weight_loader if needed
             patch_vllm_moe_model_weight_loader(llm_model)
             llm_model.load_weights(state_dict.items())
+            # Keep ZeRO-3 gathered tensors valid until vLLM finishes any queued device copies.
+            synchronize()
         del state_dict
 
     def _fix_param_name_to_vllm(self, name: str, extra_prefixes: Optional[List[str]] = None) -> str: