diff --git a/metagpt/configs/compress_msg_config.py b/metagpt/configs/compress_msg_config.py
new file mode 100644
index 000000000..c46334c12
--- /dev/null
+++ b/metagpt/configs/compress_msg_config.py
@@ -0,0 +1,32 @@
+from enum import Enum
+
+
+class CompressType(Enum):
+    """
+    Compression Type for messages. Used to compress messages under token limit.
+    - "": No compression. Default value.
+    - "post_cut_by_msg": Keep as many latest messages as possible.
+    - "post_cut_by_token": Keep as many latest messages as possible and truncate the earliest fit-in message.
+    - "pre_cut_by_msg": Keep as many earliest messages as possible.
+    - "pre_cut_by_token": Keep as many earliest messages as possible and truncate the latest fit-in message.
+    """
+
+    NO_COMPRESS = ""
+    POST_CUT_BY_MSG = "post_cut_by_msg"
+    POST_CUT_BY_TOKEN = "post_cut_by_token"
+    PRE_CUT_BY_MSG = "pre_cut_by_msg"
+    PRE_CUT_BY_TOKEN = "pre_cut_by_token"
+
+    def __missing__(self, key):
+        return self.NO_COMPRESS
+
+    @classmethod
+    def get_type(cls, type_name):
+        for member in cls:
+            if member.value == type_name:
+                return member
+        return cls.NO_COMPRESS
+
+    @classmethod
+    def cut_types(cls):
+        return [member for member in cls if "cut" in member.value]
diff --git a/metagpt/configs/llm_config.py b/metagpt/configs/llm_config.py
index 657c1a70b..c5605be21 100644
--- a/metagpt/configs/llm_config.py
+++ b/metagpt/configs/llm_config.py
@@ -10,6 +10,7 @@ from typing import Optional
 
 from pydantic import field_validator
 
+from metagpt.configs.compress_msg_config import CompressType
 from metagpt.const import LLM_API_TIMEOUT
 from metagpt.utils.yaml_model import YamlModel
 
@@ -87,7 +88,7 @@ class LLMConfig(YamlModel):
     calc_usage: bool = True
 
     # Compress request messages under token limit
-    compress_type: str = ""
+    compress_type: CompressType = CompressType.NO_COMPRESS
 
     @field_validator("api_key")
     @classmethod
@@ -100,3 +101,8 @@ class LLMConfig(YamlModel):
     @classmethod
     def check_timeout(cls, v):
         return v or LLM_API_TIMEOUT
+
+    @field_validator("compress_type")
+    @classmethod
+    def check_compress_type(cls, v):
+        return CompressType.get_type(v)
diff --git a/metagpt/provider/base_llm.py b/metagpt/provider/base_llm.py
index 6b544375e..ac09c19f7 100644
--- a/metagpt/provider/base_llm.py
+++ b/metagpt/provider/base_llm.py
@@ -10,7 +10,7 @@ from __future__ import annotations
 
 import json
 from abc import ABC, abstractmethod
-from typing import Literal, Optional, Union
+from typing import Optional, Union
 
 from openai import AsyncOpenAI
 from pydantic import BaseModel
@@ -22,6 +22,7 @@ from tenacity import (
     wait_random_exponential,
 )
 
+from metagpt.configs.compress_msg_config import CompressType
 from metagpt.configs.llm_config import LLMConfig
 from metagpt.const import LLM_API_TIMEOUT, USE_CONFIG_TIMEOUT
 from metagpt.logs import logger
@@ -279,23 +280,18 @@ class BaseLLM(ABC):
     def compress_messages(
         self,
         messages: list[dict],
-        compress_type: Literal["post_cut_by_msg", "post_cut_by_token", "pre_cut_by_msg", "pre_cut_by_token", ""] = "",
+        compress_type: CompressType = CompressType.NO_COMPRESS,
         max_token: int = 128000,
         threshold: float = 0.8,
     ) -> list[dict]:
         """Compress messages to fit within the token limit.
         Args:
             messages (list[dict]): List of messages to compress.
-            compress_type (str, optional): Compression strategy.
-                - "post_cut_by_msg": Keep as many latest messages as possible.
-                - "post_cut_by_token": Keep as many latest messages as possible and truncate the earliest fit-in message.
-                - "pre_cut_by_msg": Keep as many earliest messages as possible.
-                - "pre_cut_by_token": Keep as many earliest messages as possible and truncate the latest fit-in message.
-                - "": No compression. Default value.
+            compress_type (CompressType, optional): Compression strategy. Defaults to CompressType.NO_COMPRESS.
             max_token (int, optional): Maximum token limit. Defaults to 128000. Not effective if token limit can be found in TOKEN_MAX.
             threshold (float): Token limit threshold. Defaults to 0.8. Reserve 20% of the token limit for completion message.
         """
-        if not compress_type:
+        if compress_type == CompressType.NO_COMPRESS:
             return messages
 
         current_token_count = 0
@@ -318,7 +314,7 @@ class BaseLLM(ABC):
         compressed.extend(system_msgs)
         current_token_count += self.count_tokens(system_msgs)
 
-        if compress_type in ["post_cut_by_msg", "post_cut_by_token"]:
+        if compress_type in [CompressType.POST_CUT_BY_TOKEN, CompressType.POST_CUT_BY_MSG]:
             # Under keep_token constraint, keep as many latest messages as possible
             for i, msg in enumerate(reversed(user_assistant_msgs)):
                 token_count = self.count_tokens([msg])
@@ -326,7 +322,7 @@ class BaseLLM(ABC):
                     compressed.insert(len(system_msgs), msg)
                     current_token_count += token_count
                 else:
-                    if compress_type == "post_cut_by_token" or len(compressed) == len(system_msgs):
+                    if compress_type == CompressType.POST_CUT_BY_TOKEN or len(compressed) == len(system_msgs):
                         # Truncate the message to fit within the remaining token count; Otherwise, discard the msg. If compressed has no user or assistant message, enforce cutting by token
                         truncated_content = msg["content"][-(keep_token - current_token_count) :]
                         compressed.insert(len(system_msgs), {"role": msg["role"], "content": truncated_content})
@@ -336,7 +332,7 @@ class BaseLLM(ABC):
                     )
                     break
 
-        elif compress_type in ["pre_cut_by_msg", "pre_cut_by_token"]:
+        elif compress_type in [CompressType.PRE_CUT_BY_TOKEN, CompressType.PRE_CUT_BY_MSG]:
             # Under keep_token constraint, keep as many earliest messages as possible
             for i, msg in enumerate(user_assistant_msgs):
                 token_count = self.count_tokens([msg])
@@ -344,7 +340,7 @@ class BaseLLM(ABC):
                     compressed.append(msg)
                     current_token_count += token_count
                 else:
-                    if compress_type == "pre_cut_by_token" or len(compressed) == len(system_msgs):
+                    if compress_type == CompressType.PRE_CUT_BY_TOKEN or len(compressed) == len(system_msgs):
                         # Truncate the message to fit within the remaining token count; Otherwise, discard the msg. If compressed has no user or assistant message, enforce cutting by token
                         truncated_content = msg["content"][: keep_token - current_token_count]
                         compressed.append({"role": msg["role"], "content": truncated_content})
diff --git a/tests/metagpt/provider/test_base_llm.py b/tests/metagpt/provider/test_base_llm.py
index 87e4bdbbb..d34ed62f1 100644
--- a/tests/metagpt/provider/test_base_llm.py
+++ b/tests/metagpt/provider/test_base_llm.py
@@ -8,6 +8,7 @@
 
 import pytest
 
+from metagpt.configs.compress_msg_config import CompressType
 from metagpt.configs.llm_config import LLMConfig
 from metagpt.provider.base_llm import BaseLLM
 from metagpt.schema import Message
@@ -106,9 +107,7 @@ async def test_async_base_llm():
     # assert resp == default_resp_cont
 
 
-@pytest.mark.parametrize(
-    "compress_type", ["post_cut_by_msg", "post_cut_by_token", "pre_cut_by_msg", "pre_cut_by_token"]
-)
+@pytest.mark.parametrize("compress_type", list(CompressType))
 def test_compress_messages_no_effect(compress_type):
     base_llm = MockBaseLLM()
     messages = [
@@ -123,9 +122,7 @@ def test_compress_messages_no_effect(compress_type):
     assert compressed == messages
 
 
-@pytest.mark.parametrize(
-    "compress_type", ["post_cut_by_msg", "post_cut_by_token", "pre_cut_by_msg", "pre_cut_by_token"]
-)
+@pytest.mark.parametrize("compress_type", CompressType.cut_types())
 def test_compress_messages_long(compress_type):
     base_llm = MockBaseLLM()
     base_llm.config.model = "test_llm"
@@ -142,7 +139,7 @@ def test_compress_messages_long(compress_type):
 
     print(compressed)
     print(len(compressed))
-    assert len(compressed) < len(messages)
+    assert 3 <= len(compressed) < len(messages)
     assert compressed[0]["role"] == "system" and compressed[1]["role"] == "system"
     assert compressed[2]["role"] != "system"
 
@@ -154,9 +151,7 @@ def test_long_messages_no_compress():
     assert len(compressed) == len(messages)
 
 
-@pytest.mark.parametrize(
-    "compress_type", ["post_cut_by_msg", "post_cut_by_token", "pre_cut_by_msg", "pre_cut_by_token"]
-)
+@pytest.mark.parametrize("compress_type", CompressType.cut_types())
 def test_compress_messages_long_no_sys_msg(compress_type):
     base_llm = MockBaseLLM()
     base_llm.config.model = "test_llm"
diff --git a/tests/metagpt/provider/test_openai.py b/tests/metagpt/provider/test_openai.py
index dde98f7a3..d292a8286 100644
--- a/tests/metagpt/provider/test_openai.py
+++ b/tests/metagpt/provider/test_openai.py
@@ -9,6 +9,7 @@ from openai.types.chat.chat_completion import Choice, CompletionUsage
 from openai.types.chat.chat_completion_message_tool_call import Function
 from PIL import Image
 
+from metagpt.configs.compress_msg_config import CompressType
 from metagpt.const import TEST_DATA_PATH
 from metagpt.llm import LLM
 from metagpt.logs import logger
@@ -202,7 +203,7 @@ def test_count_tokens_long():
 async def test_aask_long():
     llm = LLM()
     llm.config.model = "deepseek-ai/DeepSeek-Coder-V2-Instruct"  # deepseek-coder on siliconflow, limit 32k
-    llm.config.compress_type = "post_cut_by_token"
+    llm.config.compress_type = CompressType.POST_CUT_BY_TOKEN
     test_msg_content = " ".join([str(i) for i in range(100000)])  # corresponds to ~300k tokens
     messages = [
         llm._system_msg("You are a helpful assistant"),