come from : http://www.mscenter.edu.cn/blog/jeffrey/archive/2006/01/10/2400.html

//这是一个通用类：

using  System;
namespace  ChatClient
 {
    public delegate void HotkeyEventHandler(int HotKeyID);
    /// <summary>
    /// System wide hotkey wrapper. 
    ///  
    /// Robert Jeppesen
    /// Send bugs to [email protected]
    /// </summary>
    public class Hotkey : System.Windows.Forms.IMessageFilter
    {
        System.Collections.Hashtable keyIDs = new System.Collections.Hashtable();
        IntPtr hWnd;
        /// <summary>
        /// Occurs when a hotkey has been pressed.
        /// </summary>
        public event HotkeyEventHandler OnHotkey;
        public enum KeyFlags
        {
            MOD_ALT = 0x1,
            MOD_CONTROL = 0x2,
            MOD_SHIFT = 0x4,
            MOD_WIN = 0x8
        }
        [System.Runtime.InteropServices.DllImport("user32.dll")]
        public static extern UInt32 RegisterHotKey( IntPtr hWnd, UInt32 id, 
            UInt32 fsModifiers, UInt32 vk);
        [System.Runtime.InteropServices.DllImport("user32.dll")]
        public static extern UInt32 UnregisterHotKey( IntPtr hWnd, UInt32 id); 
        [System.Runtime.InteropServices.DllImport("kernel32.dll")]
        public static extern UInt32 GlobalAddAtom( String lpString );
        [System.Runtime.InteropServices.DllImport("kernel32.dll")]
        public static extern UInt32 GlobalDeleteAtom( UInt32 nAtom );
        /// <summary>
        /// Constructor.  Adds this instance to the MessageFilters so that this class can raise Hotkey events
        /// </summary>
        /// <param name="hWnd">A valid hWnd, i.e. form1.Handle</param>
        public Hotkey(IntPtr hWnd)
        {
            this.hWnd = hWnd;
            System.Windows.Forms.Application.AddMessageFilter(this);
        }
        /// <summary>
        /// Register a system wide hotkey.
        /// </summary>
        /// <param name="hWnd">form1.Handle</param>
        /// <param name="Key">Your hotkey</param>
        /// <returns>ID integer for your hotkey. Use this to know which hotkey was pressed.</returns>
        public int RegisterHotkey(System.Windows.Forms.Keys Key, KeyFlags keyflags)
        {
            UInt32 hotkeyid = GlobalAddAtom(System.Guid.NewGuid().ToString());
            RegisterHotKey( (IntPtr)hWnd, hotkeyid, (UInt32)keyflags, (UInt32)Key);
            keyIDs.Add(hotkeyid, hotkeyid);
            return (int)hotkeyid;
        }
        /// <summary>
        /// Unregister hotkeys and delete atoms.
        /// </summary>
        public void UnregisterHotkeys()
        {
            System.Windows.Forms.Application.RemoveMessageFilter(this);
            foreach (UInt32 key in keyIDs.Values)
            {
                UnregisterHotKey(hWnd, key); 
                GlobalDeleteAtom(key);
            }
        }
        public bool PreFilterMessage(ref System.Windows.Forms.Message m) 
        {
            if (m.Msg == 0x312) /*WM_HOTKEY*/
            {
                if(OnHotkey != null) 
                {
                    foreach (UInt32 key in keyIDs.Values)
                    {
                        if((UInt32)m.WParam == key)
                        {
                            OnHotkey((int)m.WParam);
                            return true;
                        }
                    }
                }
            }
            return false;
        }
    }
}

1、创建并设置热键为Ctrl+1
Hotkey hotkey;
int  Hotkey1;
hotkey = new Hotkey(this .Handle);
Hotkey1 =  hotkey.RegisterHotkey(System.Windows.Forms.Keys.D1, Hotkey.KeyFlags.MOD_CONTROL);
hotkey.OnHotkey += new HotkeyEventHandler(OnHotkey);

2、按键监视函数
public void OnHotkey(int  HotkeyID)
 {
    if(HotkeyID == Hotkey1)
    {
        this.Visible = true;
    }
    else
    {
        this.Visible = false;
    }
}