[DllImport("user32.dll", SetLastError = true)]
static extern void keybd_event(byte bVk, byte bScan, uint dwFlags, UIntPtr dwExtraInfo);
public static void PressKey(Keys key, bool up)
{
    const int KEYEVENTF_EXTENDEDKEY = 0x1;
    const int KEYEVENTF_KEYUP = 0x2;
    if (up)
    {

        keybd_event((byte)key, 0x45, KEYEVENTF_EXTENDEDKEY | KEYEVENTF_KEYUP, (UIntPtr)0);

    }
    else
    {

        keybd_event((byte)key, 0x45, KEYEVENTF_EXTENDEDKEY, (UIntPtr)0);

    }
}

需要引入命名空间：using System.Runtime.InteropServices;

调用方法：

PressKey(Keys.ControlKey, false);
PressKey(Keys.V, false);
PressKey(Keys.V, true);
PressKey(Keys.ControlKey, true);

注意：上面代码是模拟的Ctrl+V，第一个参数指定的具体的按键，第二个参数true是松开,false是按下。