下面是c#中使用DllImport的直接方法。

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

public static bool Is64Bit() 
{ 
    bool retVal; 

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

    return retVal; 
} 

我需要这样做，但我也需要能够作为一个管理员远程做到这一点，无论是哪种情况下，这似乎很适合我:

    public static bool is64bit(String host)
    {
        using (var reg = RegistryKey.OpenRemoteBaseKey(RegistryHive.LocalMachine, host))
        using (var key = reg.OpenSubKey(@"Software\Microsoft\Windows\CurrentVersion\"))
        {
            return key.GetValue("ProgramFilesDir (x86)") !=null;
        }
    }

使用此命令获取已安装的Windows体系结构:

string getOSArchitecture()
{
    string architectureStr;
    if (Directory.Exists(Environment.GetFolderPath(
                           Environment.SpecialFolder.ProgramFilesX86))) {
        architectureStr ="64-bit";
    }
    else {
        architectureStr = "32-bit";
    }
    return architectureStr;
}

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。

微软为此提供了一个代码示例:

http://1code.codeplex.com/SourceControl/changeset/view/39074#842775

它是这样的:

    /// <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 Is64BitOperatingSystem()
    {
        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.
            bool flag;
            return ((DoesWin32MethodExist("kernel32.dll", "IsWow64Process") &&
                IsWow64Process(GetCurrentProcess(), out flag)) && flag);
        }
    }

    /// <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);

还有一个可用的WMI版本(用于测试远程机器)。

还可以检查PROCESSOR_ARCHITECTURE环境变量。

它要么不存在，要么在32位Windows上被设置为“x86”。

private int GetOSArchitecture()
{
    string pa = 
        Environment.GetEnvironmentVariable("PROCESSOR_ARCHITECTURE");
    return ((String.IsNullOrEmpty(pa) || 
             String.Compare(pa, 0, "x86", 0, 3, true) == 0) ? 32 : 64);
}