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)。

我使用以下版本:

    public static bool Is64BitSystem()
    {
        if (Directory.Exists(Environment.GetEnvironmentVariable("Program Files (x86)"))) return true;
        else return false;
    }

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:

试试这个:

Environment.Is64BitOperatingSystem

Environment.Is64BitProcess

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。

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;
        }
    }