diff --git a/agentrun/utils/log.py b/agentrun/utils/log.py
index 9abde14..9f40999 100644
--- a/agentrun/utils/log.py
+++ b/agentrun/utils/log.py
@@ -6,20 +6,11 @@
 
 import logging
 import os
-import time
 
 from dotenv import load_dotenv
 
 load_dotenv()
 
-UTC8_OFFSET_SECONDS = 8 * 60 * 60
-
-
-def _utc8_converter(timestamp: float) -> time.struct_time:
-    """Return a UTC+8 ``struct_time`` for logging.Formatter."""
-
-    return time.gmtime(timestamp + UTC8_OFFSET_SECONDS)
-
 
 class CustomFormatter(logging.Formatter):
     """自定义日志格式化器 / Custom Log Formatter
@@ -57,17 +48,11 @@ def __init__(self) -> None:
                     f" {self.DIM}%(pathname)s:%(lineno)s{self.RESET}"
                     "\n%(message)s"
                 )
-            self._formatters[level] = self._create_formatter(fmt)
+            self._formatters[level] = logging.Formatter(fmt)
         self._default = logging.Formatter(
             "\n%(levelname)s [%(name)s] %(asctime)s"
             " %(pathname)s:%(lineno)s\n%(message)s"
         )
-        self._default.converter = _utc8_converter
-
-    def _create_formatter(self, fmt: str) -> logging.Formatter:
-        formatter = logging.Formatter(fmt)
-        formatter.converter = _utc8_converter
-        return formatter
 
     def format(self, record: logging.LogRecord) -> str:
         return self._formatters.get(record.levelname, self._default).format(
diff --git a/tests/unittests/test_log.py b/tests/unittests/test_log.py
deleted file mode 100644
index 65dc79d..0000000
--- a/tests/unittests/test_log.py
+++ /dev/null
@@ -1,66 +0,0 @@
-"""Unit tests for AgentRun SDK logging."""
-
-import logging
-import time
-
-import pytest
-
-from agentrun.utils.log import CustomFormatter, _utc8_converter
-
-
-def make_record(level: int, level_name: str) -> logging.LogRecord:
-    record = logging.LogRecord(
-        name="agentrun-logger",
-        level=level,
-        pathname=__file__,
-        lineno=1,
-        msg="hello",
-        args=(),
-        exc_info=None,
-    )
-    record.created = 0
-    record.levelname = level_name
-    return record
-
-
-def test_utc8_converter_is_independent_from_local_timezone():
-    assert _utc8_converter(0) == time.gmtime(8 * 60 * 60)
-
-
-def test_custom_formatter_uses_utc8_for_all_inner_formatters():
-    formatter = CustomFormatter()
-    expected = time.gmtime(8 * 60 * 60)
-
-    for inner in formatter._formatters.values():
-        assert inner.converter(0) == expected
-    assert formatter._default.converter(0) == expected
-
-
-@pytest.mark.parametrize(
-    ("level", "level_name"),
-    [
-        (logging.DEBUG, "DEBUG"),
-        (logging.INFO, "INFO"),
-        (logging.WARNING, "WARNING"),
-        (logging.ERROR, "ERROR"),
-        (logging.CRITICAL, "CRITICAL"),
-    ],
-)
-def test_custom_formatter_formats_known_levels_in_utc8(
-    level: int, level_name: str
-):
-    formatter = CustomFormatter()
-
-    output = formatter.format(make_record(level, level_name))
-
-    assert "1970-01-01 08:00:00" in output
-    assert "1970-01-01 00:00:00" not in output
-
-
-def test_custom_formatter_formats_fallback_level_in_utc8():
-    formatter = CustomFormatter()
-
-    output = formatter.format(make_record(5, "TRACE"))
-
-    assert "1970-01-01 08:00:00" in output
-    assert "1970-01-01 00:00:00" not in output