diff --git a/src/nni_manager/core/nnimanager.ts b/src/nni_manager/core/nnimanager.ts
index 0e5e5383e7..b276168be1 100644
--- a/src/nni_manager/core/nnimanager.ts
+++ b/src/nni_manager/core/nnimanager.ts
@@ -359,6 +359,7 @@ class NNIManager implements Manager {
         }
 
         const nniEnv = {
+            SDK_PROCESS: 'dispatcher',
             NNI_MODE: mode,
             NNI_CHECKPOINT_DIRECTORY: dataDirectory,
             NNI_LOG_DIRECTORY: getLogDir(),
diff --git a/src/sdk/pynni/nni/__init__.py b/src/sdk/pynni/nni/__init__.py
index 87cef1074c..a8cd78bbf7 100644
--- a/src/sdk/pynni/nni/__init__.py
+++ b/src/sdk/pynni/nni/__init__.py
@@ -1,9 +1,12 @@
 # Copyright (c) Microsoft Corporation.
 # Licensed under the MIT license.
 
-from .trial import *
-from .smartparam import *
-from .nas_utils import training_update
+from .env_vars import dispatcher_env_vars
+
+if dispatcher_env_vars.SDK_PROCESS != 'dispatcher':
+    from .trial import *
+    from .smartparam import *
+    from .nas_utils import training_update
 
 class NoMoreTrialError(Exception):
     def __init__(self, ErrorInfo):
diff --git a/src/sdk/pynni/nni/env_vars.py b/src/sdk/pynni/nni/env_vars.py
index 20989ed66c..5227956012 100644
--- a/src/sdk/pynni/nni/env_vars.py
+++ b/src/sdk/pynni/nni/env_vars.py
@@ -16,6 +16,7 @@
 ]
 
 _dispatcher_env_var_names = [
+    'SDK_PROCESS',
     'NNI_MODE',
     'NNI_CHECKPOINT_DIRECTORY',
     'NNI_LOG_DIRECTORY',
diff --git a/src/sdk/pynni/nni/hyperopt_tuner/hyperopt_tuner.py b/src/sdk/pynni/nni/hyperopt_tuner/hyperopt_tuner.py
index c0a64ffa39..466c29c484 100644
--- a/src/sdk/pynni/nni/hyperopt_tuner/hyperopt_tuner.py
+++ b/src/sdk/pynni/nni/hyperopt_tuner/hyperopt_tuner.py
@@ -11,7 +11,6 @@
 import hyperopt as hp
 import numpy as np
 from nni.tuner import Tuner
-from nni.nas_utils import rewrite_nas_space
 from nni.utils import NodeType, OptimizeMode, extract_scalar_reward, split_index
 
 logger = logging.getLogger('hyperopt_AutoML')
@@ -226,7 +225,6 @@ def _choose_tuner(self, algorithm_name):
             return hp.anneal.suggest
         raise RuntimeError('Not support tuner algorithm in hyperopt.')
 
-    @rewrite_nas_space
     def update_search_space(self, search_space):
         """
         Update search space definition in tuner by search_space in parameters.
diff --git a/src/sdk/pynni/nni/platform/__init__.py b/src/sdk/pynni/nni/platform/__init__.py
index 6f79fd3077..da3daf6c89 100644
--- a/src/sdk/pynni/nni/platform/__init__.py
+++ b/src/sdk/pynni/nni/platform/__init__.py
@@ -1,7 +1,9 @@
 # Copyright (c) Microsoft Corporation.
 # Licensed under the MIT license.
 
-from ..env_vars import trial_env_vars
+from ..env_vars import trial_env_vars, dispatcher_env_vars
+
+assert dispatcher_env_vars.SDK_PROCESS != 'dispatcher'
 
 if trial_env_vars.NNI_PLATFORM is None:
     from .standalone import *