diff --git a/MultiThread/MultiThread.sln b/MultiThread/MultiThread.sln
index 4d00f16..f99f77c 100644
--- a/MultiThread/MultiThread.sln
+++ b/MultiThread/MultiThread.sln
@@ -7,6 +7,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Server", "Server\Server.csp
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Client", "Client\Client.csproj", "{A7321FF5-0046-4C28-BFE6-DE87E6C8E60C}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ThreadSyncTest", "ThreadSyncTest\ThreadSyncTest.csproj", "{525F636D-8678-47E4-BC62-690B17052E76}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -21,6 +23,10 @@ Global
 		{A7321FF5-0046-4C28-BFE6-DE87E6C8E60C}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{A7321FF5-0046-4C28-BFE6-DE87E6C8E60C}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{A7321FF5-0046-4C28-BFE6-DE87E6C8E60C}.Release|Any CPU.Build.0 = Release|Any CPU
+		{525F636D-8678-47E4-BC62-690B17052E76}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{525F636D-8678-47E4-BC62-690B17052E76}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{525F636D-8678-47E4-BC62-690B17052E76}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{525F636D-8678-47E4-BC62-690B17052E76}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
diff --git a/MultiThread/ThreadSyncTest/Program.cs b/MultiThread/ThreadSyncTest/Program.cs
new file mode 100644
index 0000000..a615ee2
--- /dev/null
+++ b/MultiThread/ThreadSyncTest/Program.cs
@@ -0,0 +1,62 @@
+namespace ThreadSyncTest;
+
+internal class Program
+{
+	static void Main(string[] args)
+	{
+		int num = 0;
+		object obj = new object();
+
+		Thread t1 = new Thread(() =>
+		{
+			for (int i = 0; i < 1000000; i++)
+			{
+				lock (obj)
+				{
+					num++;
+				}
+
+				//try
+				//{
+				//	Monitor.Enter(obj);
+				//	num++; // Critical section
+				//}
+				//finally
+				//{
+				//	Monitor.Exit(obj);
+				//}
+			}
+		});
+
+		Thread t2 = new Thread(() =>
+		{
+			for (int i = 0; i < 1000000; i++)
+			{
+				lock (obj)
+				{
+					num++;
+				}
+
+				//try
+				//{
+				//	Monitor.Enter(obj);
+				//	num++; // Critical section
+				//}
+				//finally
+				//{
+				//	Monitor.Exit(obj);
+				//}
+			}
+		});
+
+		t1.Start();
+		t2.Start();
+
+		t1.Join();
+		t2.Join();
+
+		Console.WriteLine(num);
+
+		Console.ReadLine();
+	}
+}
\ No newline at end of file
diff --git a/MultiThread/ThreadSyncTest/ThreadSyncTest.csproj b/MultiThread/ThreadSyncTest/ThreadSyncTest.csproj
new file mode 100644
index 0000000..74abf5c
--- /dev/null
+++ b/MultiThread/ThreadSyncTest/ThreadSyncTest.csproj
@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>