diff --git a/trinity/cli/launcher.py b/trinity/cli/launcher.py
index 59e0387172..9f9c799872 100644
--- a/trinity/cli/launcher.py
+++ b/trinity/cli/launcher.py
@@ -129,7 +129,8 @@ def run(config_path: str):
         data_config.dj_config_path or data_config.dj_process_desc
     ):
         activate_data_module(data_config.data_workflow_url, config_path)
-    ray.init()
+    if not ray.is_initialized():
+        ray.init()
     if config.mode == "explore":
         explore(config)
     elif config.mode == "train":
diff --git a/trinity/common/models/vllm_worker.py b/trinity/common/models/vllm_worker.py
index 13fd786a94..f42d843c3f 100644
--- a/trinity/common/models/vllm_worker.py
+++ b/trinity/common/models/vllm_worker.py
@@ -5,7 +5,7 @@
 import torch.distributed
 from vllm.worker.worker import Worker
 
-from trinity.utils.distributed import init_process_group
+from trinity.utils.distributed import init_process_group, is_ipv6_address
 from trinity.utils.log import get_logger
 
 logger = get_logger(__name__)
@@ -43,9 +43,15 @@ def init_process_group(
             )
             self._weight_update_rank = torch.distributed.get_rank() + rank_offset
 
+        if is_ipv6_address(master_address):
+            # using tcp://ipv6:port will lead to ValueError
+            init_method = f"tcp://[{master_address}]:{master_port}"
+        else:
+            init_method = f"tcp://{master_address}:{master_port}"
+
         self._model_update_group = init_process_group(
             backend=backend,
-            init_method=f"tcp://{master_address}:{master_port}",
+            init_method=init_method,
             world_size=world_size,
             rank=self._weight_update_rank,
             group_name=group_name,
diff --git a/trinity/trainer/verl/fsdp_workers.py b/trinity/trainer/verl/fsdp_workers.py
index ce3365354b..94f5939f53 100644
--- a/trinity/trainer/verl/fsdp_workers.py
+++ b/trinity/trainer/verl/fsdp_workers.py
@@ -51,7 +51,7 @@
 from verl.workers.sharding_manager.fsdp_ulysses import FSDPUlyssesShardingManager
 
 from trinity.common.constants import AlgorithmType
-from trinity.utils.distributed import init_process_group
+from trinity.utils.distributed import init_process_group, is_ipv6_address
 
 logger = logging.getLogger(__file__)
 logger.setLevel(os.getenv("VERL_PPO_LOGGING_LEVEL", "WARN"))
@@ -592,9 +592,15 @@ def setup_weight_sync_group(self):
                 setup_ref = explorer.setup_weight_sync_group.remote(
                     master_address, master_port, self.state_dict_meta
                 )
+                if is_ipv6_address(master_address):
+                    # using tcp://ipv6:port will lead to ValueError
+                    init_method = f"tcp://[{master_address}]:{master_port}"
+                else:
+                    init_method = f"tcp://{master_address}:{master_port}"
+
                 self._model_update_group = init_process_group(
                     backend=backend,
-                    init_method=f"tcp://{master_address}:{master_port}",
+                    init_method=init_method,
                     world_size=world_size,
                     rank=0,
                     group_name=group_name,
diff --git a/trinity/utils/distributed.py b/trinity/utils/distributed.py
index 898c763e28..5111b41449 100644
--- a/trinity/utils/distributed.py
+++ b/trinity/utils/distributed.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 """For distributed training with multiple process groups."""
+import ipaddress
 from datetime import timedelta
 from typing import Any, Optional, Union
 
@@ -15,6 +16,14 @@
 )
 
 
+def is_ipv6_address(ip_str: str) -> bool:
+    try:
+        ip = ipaddress.ip_address(ip_str)
+        return isinstance(ip, ipaddress.IPv6Address)
+    except ValueError:
+        return False
+
+
 def init_process_group(
     backend: Union[str, Backend] = None,
     init_method: Optional[str] = None,