diff --git a/qlib/__init__.py b/qlib/__init__.py
index b43dd6fc42a..8a306787786 100644
--- a/qlib/__init__.py
+++ b/qlib/__init__.py
@@ -27,8 +27,8 @@ def init(default_conf="client", **kwargs):
 
     Parameters
     ----------
-    default_conf: str
-        the default value is client. Accepted values: client/server.
+    default_conf: str or ModeType
+        the default value is client. Accepted values: ModeType.CLIENT/ModeType.SERVER (or "client"/"server").
     **kwargs :
         clear_mem_cache: str
             the default value is True;
diff --git a/qlib/config.py b/qlib/config.py
index 4e5d62564f7..c9e289e103b 100644
--- a/qlib/config.py
+++ b/qlib/config.py
@@ -22,7 +22,7 @@
 from typing import Callable, Optional, Union
 from typing import TYPE_CHECKING
 
-from qlib.constant import REG_CN, REG_US, REG_TW
+from qlib.constant import REG_CN, REG_US, REG_TW, ModeType
 
 if TYPE_CHECKING:
     from qlib.utils.time import Freq
@@ -247,7 +247,7 @@ def register_from_C(config, skip_register=True):
 }
 
 MODE_CONF = {
-    "server": {
+    ModeType.SERVER: {
         # config it in qlib.init()
         "provider_uri": "",
         # redis
@@ -260,7 +260,7 @@ def register_from_C(config, skip_register=True):
         "local_cache_path": Path("~/.cache/qlib_simple_cache").expanduser().resolve(),
         "mount_path": None,
     },
-    "client": {
+    ModeType.CLIENT: {
         # config it in user's own code
         "provider_uri": QSETTINGS.provider_uri,
         # cache
@@ -385,7 +385,7 @@ def get_data_uri(self, freq: Optional[Union[str, Freq]] = None) -> Path:
 
     def set_mode(self, mode):
         # raise KeyError
-        self.update(MODE_CONF[mode])
+        self.update(MODE_CONF[ModeType(mode)])
         # TODO: update region based on kwargs
 
     def set_region(self, region):
@@ -420,7 +420,7 @@ def resolve_path(self):
         self["provider_uri"] = _provider_uri
         self["mount_path"] = _mount_path
 
-    def set(self, default_conf: str = "client", **kwargs):
+    def set(self, default_conf: Union[str, ModeType] = ModeType.CLIENT, **kwargs):
         """
         configure qlib based on the input parameters
 
@@ -435,8 +435,8 @@ def set(self, default_conf: str = "client", **kwargs):
 
         Parameters
         ----------
-        default_conf : str
-            the default config template chosen by user: "server", "client"
+        default_conf : str or ModeType
+            the default config template chosen by user: ModeType.SERVER, ModeType.CLIENT (or "server", "client")
         """
         from .utils import set_log_with_config, get_module_logger, can_use_cache  # pylint: disable=C0415
 
diff --git a/qlib/constant.py b/qlib/constant.py
index ac6c76ae22c..f9daa677a78 100644
--- a/qlib/constant.py
+++ b/qlib/constant.py
@@ -2,6 +2,7 @@
 # Licensed under the MIT License.
 
 # REGION CONST
+from enum import Enum
 from typing import TypeVar
 
 import numpy as np
@@ -20,3 +21,10 @@
 ONE_MIN = pd.Timedelta("1min")
 EPS_T = pd.Timedelta("1s")  # use 1 second to exclude the right interval point
 float_or_ndarray = TypeVar("float_or_ndarray", float, np.ndarray)
+
+
+class ModeType(str, Enum):
+    """Mode type for qlib initialization: client or server."""
+
+    CLIENT = "client"
+    SERVER = "server"