diff --git a/GFramework.Core.Abstractions/logging/LogContext.cs b/GFramework.Core.Abstractions/logging/LogContext.cs
index 0f54d16..6effb1d 100644
--- a/GFramework.Core.Abstractions/logging/LogContext.cs
+++ b/GFramework.Core.Abstractions/logging/LogContext.cs
@@ -15,7 +15,7 @@ public sealed class LogContext : IDisposable
         _key = key;
 
         var current = _context.Value;
-        if (current != null && current.TryGetValue(key, out var prev))
+        if (current?.TryGetValue(key, out var prev) == true)
         {
             _previousValue = prev;
             _hadPreviousValue = true;
@@ -103,21 +103,14 @@ public sealed class LogContext : IDisposable
     /// <summary>
     ///     组合多个可释放对象
     /// </summary>
-    private sealed class CompositeDisposable : IDisposable
+    private sealed class CompositeDisposable(IDisposable[] disposables) : IDisposable
     {
-        private readonly IDisposable[] _disposables;
-
-        public CompositeDisposable(IDisposable[] disposables)
-        {
-            _disposables = disposables;
-        }
-
         public void Dispose()
         {
             // 按相反顺序释放
-            for (int i = _disposables.Length - 1; i >= 0; i--)
+            for (int i = disposables.Length - 1; i >= 0; i--)
             {
-                _disposables[i].Dispose();
+                disposables[i].Dispose();
             }
         }
     }
diff --git a/GFramework.Core.Tests/logging/AsyncLogAppenderTests.cs b/GFramework.Core.Tests/logging/AsyncLogAppenderTests.cs
index dab71c7..eb5bd3d 100644
--- a/GFramework.Core.Tests/logging/AsyncLogAppenderTests.cs
+++ b/GFramework.Core.Tests/logging/AsyncLogAppenderTests.cs
@@ -30,14 +30,14 @@ public class AsyncLogAppenderTests
         var innerAppender = new SlowAppender(delayMs: 100);
         using var asyncAppender = new AsyncLogAppender(innerAppender, bufferSize: 1000);
 
-        var startTime = DateTime.Now;
+        var startTime = DateTime.UtcNow;
         for (int i = 0; i < 10; i++)
         {
-            var entry = new LogEntry(DateTime.Now, LogLevel.Info, "TestLogger", $"Message {i}", null, null);
+            var entry = new LogEntry(DateTime.UtcNow, LogLevel.Info, "TestLogger", $"Message {i}", null, null);
             asyncAppender.Append(entry);
         }
 
-        var elapsed = (DateTime.Now - startTime).TotalMilliseconds;
+        var elapsed = (DateTime.UtcNow - startTime).TotalMilliseconds;
 
         // 异步写入应该非常快（< 100ms），不应该等待内部 Appender
         Assert.That(elapsed, Is.LessThan(100));
@@ -51,7 +51,7 @@ public class AsyncLogAppenderTests
         {
             for (int i = 0; i < 10; i++)
             {
-                var entry = new LogEntry(DateTime.Now, LogLevel.Info, "TestLogger", $"Message {i}", null, null);
+                var entry = new LogEntry(DateTime.UtcNow, LogLevel.Info, "TestLogger", $"Message {i}", null, null);
                 asyncAppender.Append(entry);
             }
 
@@ -69,7 +69,7 @@ public class AsyncLogAppenderTests
 
         for (int i = 0; i < 100; i++)
         {
-            var entry = new LogEntry(DateTime.Now, LogLevel.Info, "TestLogger", $"Message {i}", null, null);
+            var entry = new LogEntry(DateTime.UtcNow, LogLevel.Info, "TestLogger", $"Message {i}", null, null);
             asyncAppender.Append(entry);
         }
 
@@ -86,7 +86,7 @@ public class AsyncLogAppenderTests
         {
             for (int i = 0; i < 50; i++)
             {
-                var entry = new LogEntry(DateTime.Now, LogLevel.Info, "TestLogger", $"Message {i}", null, null);
+                var entry = new LogEntry(DateTime.UtcNow, LogLevel.Info, "TestLogger", $"Message {i}", null, null);
                 asyncAppender.Append(entry);
             }
         } // Dispose 会等待所有日志处理完成
@@ -101,7 +101,7 @@ public class AsyncLogAppenderTests
         var asyncAppender = new AsyncLogAppender(innerAppender);
         asyncAppender.Dispose();
 
-        var entry = new LogEntry(DateTime.Now, LogLevel.Info, "TestLogger", "Test", null, null);
+        var entry = new LogEntry(DateTime.UtcNow, LogLevel.Info, "TestLogger", "Test", null, null);
 
         Assert.Throws<ObjectDisposedException>(() => asyncAppender.Append(entry));
     }
@@ -114,7 +114,7 @@ public class AsyncLogAppenderTests
 
         for (int i = 0; i < 10; i++)
         {
-            var entry = new LogEntry(DateTime.Now, LogLevel.Info, "TestLogger", $"Message {i}", null, null);
+            var entry = new LogEntry(DateTime.UtcNow, LogLevel.Info, "TestLogger", $"Message {i}", null, null);
             asyncAppender.Append(entry);
         }
 
@@ -136,7 +136,7 @@ public class AsyncLogAppenderTests
             {
                 for (int i = 0; i < 100; i++)
                 {
-                    var entry = new LogEntry(DateTime.Now, LogLevel.Info, "TestLogger",
+                    var entry = new LogEntry(DateTime.UtcNow, LogLevel.Info, "TestLogger",
                         $"Thread {threadId} Message {i}", null, null);
                     asyncAppender.Append(entry);
                 }
@@ -160,7 +160,7 @@ public class AsyncLogAppenderTests
         {
             for (int i = 0; i < 10; i++)
             {
-                var entry = new LogEntry(DateTime.Now, LogLevel.Info, "TestLogger", $"Message {i}", null, null);
+                var entry = new LogEntry(DateTime.UtcNow, LogLevel.Info, "TestLogger", $"Message {i}", null, null);
                 asyncAppender.Append(entry);
             }
         });
diff --git a/GFramework.Core/logging/CompositeLogger.cs b/GFramework.Core/logging/CompositeLogger.cs
index 06dba6c..253cd80 100644
--- a/GFramework.Core/logging/CompositeLogger.cs
+++ b/GFramework.Core/logging/CompositeLogger.cs
@@ -50,7 +50,7 @@ public sealed class CompositeLogger : AbstractLogger, IDisposable
     protected override void Write(LogLevel level, string message, Exception? exception)
     {
         var entry = new LogEntry(
-            DateTime.Now,
+            DateTime.UtcNow,
             level,
             Name(),
             message,
@@ -78,7 +78,7 @@ public sealed class CompositeLogger : AbstractLogger, IDisposable
             : null;
 
         var entry = new LogEntry(
-            DateTime.Now,
+            DateTime.UtcNow,
             level,
             Name(),
             message,
@@ -108,7 +108,7 @@ public sealed class CompositeLogger : AbstractLogger, IDisposable
             : null;
 
         var entry = new LogEntry(
-            DateTime.Now,
+            DateTime.UtcNow,
             level,
             Name(),
             message,
diff --git a/GFramework.Core/logging/formatters/JsonLogFormatter.cs b/GFramework.Core/logging/formatters/JsonLogFormatter.cs
index 83e6820..407aac7 100644
--- a/GFramework.Core/logging/formatters/JsonLogFormatter.cs
+++ b/GFramework.Core/logging/formatters/JsonLogFormatter.cs
@@ -24,7 +24,7 @@ public sealed class JsonLogFormatter : ILogFormatter
         var logObject = new Dictionary<string, object?>
         {
             ["timestamp"] = entry.Timestamp.ToString("O"), // ISO 8601 格式
-            ["level"] = entry.Level.ToString().ToUpper(),
+            ["level"] = entry.Level.ToString().ToUpperInvariant(),
             ["logger"] = entry.LoggerName,
             ["message"] = entry.Message
         };