diff --git a/agentrun/utils/log.py b/agentrun/utils/log.py
index 9f40999..9abde14 100644
--- a/agentrun/utils/log.py
+++ b/agentrun/utils/log.py
@@ -6,11 +6,20 @@
 
 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
@@ -48,11 +57,17 @@ def __init__(self) -> None:
                     f" {self.DIM}%(pathname)s:%(lineno)s{self.RESET}"
                     "\n%(message)s"
                 )
-            self._formatters[level] = logging.Formatter(fmt)
+            self._formatters[level] = self._create_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
new file mode 100644
index 0000000..65dc79d
--- /dev/null
+++ b/tests/unittests/test_log.py
@@ -0,0 +1,66 @@
+"""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