diff --git a/ucloud/scheduler/helper.py b/ucloud/scheduler/helper.py
index ba577d6..1754045 100755
--- a/ucloud/scheduler/helper.py
+++ b/ucloud/scheduler/helper.py
@@ -6,7 +6,7 @@ import bitmath
 from ucloud.common.host import HostStatus
 from ucloud.common.request import RequestEntry, RequestType
 from ucloud.common.vm import VMStatus
-from ucloud.config import vm_pool, host_pool, request_pool, env_vars
+from ucloud.config import vm_pool, host_pool, request_pool, config
 
 
 def accumulated_specs(vms_specs):
@@ -106,7 +106,7 @@ def assign_host(vm):
     r = RequestEntry.from_scratch(type=RequestType.StartVM,
                                   uuid=vm.uuid,
                                   hostname=vm.hostname,
-                                  request_prefix=env_vars.get("REQUEST_PREFIX"))
+                                  request_prefix=config['etcd']['REQUEST_PREFIX'])
     request_pool.put(r)
 
     vm.log.append("VM scheduled for starting")