下面是Windows管理规范(WMI)方法:

string _osVersion = "";
string _osServicePack = "";
string _osArchitecture = "";

ManagementObjectSearcher searcher = new ManagementObjectSearcher("select * from Win32_OperatingSystem");
ManagementObjectCollection collection = searcher.Get();

foreach (ManagementObject mbo in collection)
{
    _osVersion = mbo.GetPropertyValue("Caption").ToString();
    _osServicePack = string.Format("{0}.{1}", mbo.GetPropertyValue("ServicePackMajorVersion").ToString(), mbo.GetPropertyValue("ServicePackMinorVersion").ToString());

    try
    {
        _osArchitecture = mbo.GetPropertyValue("OSArchitecture").ToString();
    }
    catch
    {
        // OSArchitecture only supported on Windows 7/Windows Server 2008
    }
}

Console.WriteLine("osVersion     : " + _osVersion);
Console.WriteLine("osServicePack : " + _osServicePack);
Console.WriteLine("osArchitecture: " + _osArchitecture);

/////////////////////////////////////////
// Test on Windows 7 64-bit
//
// osVersion     : Microsoft Windows 7 Professional
// osservicePack : 1.0
// osArchitecture: 64-bit

/////////////////////////////////////////
// Test on Windows Server 2008 64-bit
//    --The extra r's come from the registered trademark
//
// osVersion     : Microsoftr Windows Serverr 2008 Standard
// osServicePack : 1.0
// osArchitecture: 64-bit

/////////////////////////////////////////
// Test on Windows Server 2003 32-bit
//    --OSArchitecture property not supported on W2K3
//
// osVersion     : Microsoft(R) Windows(R) Server 2003, Standard Edition
// osServicePack : 2.0
// osArchitecture:

最快的方式:

if(IntPtr.Size == 8) {
    // 64 bit machine
} else if(IntPtr.Size == 4)  {
    // 32 bit machine
} 

注意:这是非常直接的，只有当程序不强制作为32位进程执行时(例如，在项目设置中通过<Prefer32Bit>true</Prefer32Bit>)，才能在64位上正确工作。

对不起，是VB的代码。NET，但是很容易移植到c#。 它可以在Win7, x64和.Net Framework 4.8上正常工作:

Dim r As String = ""
Using searcher As ManagementObjectSearcher = New System.Management.ManagementObjectSearcher("SELECT * FROM Win32_OperatingSystem")
    Dim Information As ManagementObjectCollection = searcher.Get()
    If Information IsNot Nothing Then
        For Each obj As ManagementObject In Information
            r = obj("Caption").ToString() & _
            " - " & _
            obj("OSArchitecture").ToString() ' <--- !!! "64-bit" shown here
        Next
    End If
    MessageBox.Show(r)
End Using

这是一个基于微软http://1code.codeplex.com/SourceControl/changeset/view/39074#842775代码的解决方案。它使用扩展方法方便代码重用。

下面是一些可能的用法:

bool bIs64BitOS = System.Environment.OSVersion.IsWin64BitOS();

bool bIs64BitProc = System.Diagnostics.Process.GetCurrentProcess().Is64BitProc();

//Hosts the extension methods  
public static class OSHelperTools  
{  
    /// <summary>     
    /// The function determines whether the current operating system is a      
    /// 64-bit operating system.     
    /// </summary>     
    /// <returns>     
    /// The function returns true if the operating system is 64-bit;      
    /// otherwise, it returns false.     
    /// </returns>    
    public static bool IsWin64BitOS(this OperatingSystem os)  
    {  
        if (IntPtr.Size == 8)  
        // 64-bit programs run only on Win64           
            return true;   
        else// 32-bit programs run on both 32-bit and 64-bit Windows     
        {   // Detect whether the current process is a 32-bit process                
            // running on a 64-bit system.               
            return Process.GetCurrentProcess().Is64BitProc();  
        }  
    }  

    /// <summary>  
    /// Checks if the process is 64 bit  
    /// </summary>  
    /// <param name="os"></param>  
    /// <returns>  
    /// The function returns true if the process is 64-bit;        
    /// otherwise, it returns false.  
    /// </returns>    
    public static bool Is64BitProc(this System.Diagnostics.Process p)  
    {  
        // 32-bit programs run on both 32-bit and 64-bit Windows           
        // Detect whether the current process is a 32-bit process                
        // running on a 64-bit system.               
        bool result;  
        return ((DoesWin32MethodExist("kernel32.dll", "IsWow64Process") && IsWow64Process(p.Handle, out result)) && result);  
    }  

    /// <summary>     
    /// The function determins whether a method exists in the export      
    /// table of a certain module.     
    /// </summary>     
    /// <param name="moduleName">The name of the module</param>     
    /// <param name="methodName">The name of the method</param>     
    /// <returns>     
    /// The function returns true if the method specified by methodName      
    /// exists in the export table of the module specified by moduleName.     
    /// </returns>       
    static bool DoesWin32MethodExist(string moduleName, string methodName)  
    {  
        IntPtr moduleHandle = GetModuleHandle(moduleName);  
        if (moduleHandle == IntPtr.Zero)  
            return false;    
        return (GetProcAddress(moduleHandle, methodName) != IntPtr.Zero);   
    }  
    [DllImport("kernel32.dll")]  
    static extern IntPtr GetCurrentProcess();  

    [DllImport("kernel32.dll", CharSet = CharSet.Auto)]  
    static extern IntPtr GetModuleHandle(string moduleName);  

    [DllImport("kernel32", CharSet = CharSet.Auto, SetLastError = true)]  
    static extern IntPtr GetProcAddress(IntPtr hModule, [MarshalAs(UnmanagedType.LPStr)]string procName);  

    [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]  
    [return: MarshalAs(UnmanagedType.Bool)]  
    static extern bool IsWow64Process(IntPtr hProcess, out bool wow64Process);  
}

这个问题是针对。net 2.0的，但仍然会在谷歌搜索中出现，这里没有人提到，自从。net标准1.1 / .NET核心1.0以来，现在有一个更好的方法来了解CPU架构:

System.Runtime.InteropServices.RuntimeInformation.ProcessArchitecture

理论上，这应该能够区分x64和Arm64，尽管我自己没有测试它。

请参见文档。

完整的答案是这样的(摘自stefan-mg, ripper234和BobbyShaftoe的答案):

    [DllImport("kernel32.dll", SetLastError = true, CallingConvention = CallingConvention.Winapi)]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static extern bool IsWow64Process([In] IntPtr hProcess, [Out] out bool lpSystemInfo);

    private bool Is64Bit()
    {
        if (IntPtr.Size == 8 || (IntPtr.Size == 4 && Is32BitProcessOn64BitProcessor()))
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    private bool Is32BitProcessOn64BitProcessor()
    {
        bool retVal;

        IsWow64Process(Process.GetCurrentProcess().Handle, out retVal);

        return retVal;
    } 

首先检查您是否处于64位进程中。如果不是，检查32位进程是否是Wow64Process。