diff --git a/src/memos/configs/mem_cube.py b/src/memos/configs/mem_cube.py
index 4bd709fab..2092cfdea 100644
--- a/src/memos/configs/mem_cube.py
+++ b/src/memos/configs/mem_cube.py
@@ -36,7 +36,7 @@ class GeneralMemCubeConfig(BaseMemCubeConfig):
         description="User ID for the MemCube. This is used to distinguish between different users' memories.",
     )
     cube_id: str = Field(
-        str(uuid.uuid4()),
+        default_factory=lambda: str(uuid.uuid4()),
         description="Cube ID for the MemCube. This is used to distinguish between different MemCubes.",
     )
     text_mem: MemoryConfigFactory = Field(
diff --git a/src/memos/configs/mem_os.py b/src/memos/configs/mem_os.py
index 549e55792..db0fd7bcd 100644
--- a/src/memos/configs/mem_os.py
+++ b/src/memos/configs/mem_os.py
@@ -17,7 +17,7 @@ class MOSConfig(BaseConfig):
         description="User ID for the MOS. This is used to distinguish between different users' memories.",
     )
     session_id: str = Field(
-        default=str(uuid.uuid4()),
+        default_factory=lambda: str(uuid.uuid4()),
         description="Session ID for the MOS. This is used to distinguish between different dialogue",
     )
     chat_model: LLMConfigFactory = Field(
diff --git a/tests/configs/test_mem_cube.py b/tests/configs/test_mem_cube.py
index c50195558..7c594637f 100644
--- a/tests/configs/test_mem_cube.py
+++ b/tests/configs/test_mem_cube.py
@@ -28,9 +28,9 @@ def test_base_mem_cube_config():
 def test_general_mem_cube_config():
     check_config_base_class(
         GeneralMemCubeConfig,
-        factory_fields=["text_mem", "act_mem", "para_mem", "pref_mem"],
+        factory_fields=["cube_id", "text_mem", "act_mem", "para_mem", "pref_mem"],
         required_fields=[],
-        optional_fields=["config_filename", "user_id", "cube_id"],
+        optional_fields=["config_filename", "user_id"],
         reserved_fields=["model_schema"],
     )
 
@@ -44,3 +44,14 @@ def test_general_mem_cube_config():
 
     config_data["text_mem"]["backend"] = "kv_cache"  # Invalid backend for text_mem
     check_config_instantiation_invalid(GeneralMemCubeConfig, config_data)
+
+
+def test_general_mem_cube_config_generates_unique_default_cube_ids():
+    with open("examples/data/mem_cube_2/config.json") as f:
+        config_data = json.load(f)
+    config_data.pop("cube_id", None)
+
+    first_config = GeneralMemCubeConfig(**config_data)
+    second_config = GeneralMemCubeConfig(**config_data)
+
+    assert first_config.cube_id != second_config.cube_id
diff --git a/tests/configs/test_mem_os.py b/tests/configs/test_mem_os.py
new file mode 100644
index 000000000..9e3474826
--- /dev/null
+++ b/tests/configs/test_mem_os.py
@@ -0,0 +1,8 @@
+from memos.configs.mem_os import MOSConfig
+
+
+def test_mos_config_generates_unique_default_session_ids():
+    first_config = MOSConfig.model_construct(chat_model=None, mem_reader=None)
+    second_config = MOSConfig.model_construct(chat_model=None, mem_reader=None)
+
+    assert first_config.session_id != second_config.session_id