看看这个参考:http: //msdn.microsoft.com/en-us/library/system.windows.forms.timer.aspx
它说:
  此 Windows 计时器专为使用 UI 线程执行处理的单线程环境而设计
所以这是单线程的,因为你的计时器的间隔是一样的。它们将按顺序处理。您应该改用 System.Threading.Thread。请参见下面的示例。您可以创建一个参数化线程对象,该对象将字符串参数作为 sendkeys 应该在该线程上发送的内容。并启动两个或更多线程。
using System;
using System.Threading;
// Simple threading scenario:  Start a static method running 
// on a second thread. 
public class ThreadExample {
    // The ThreadProc method is called when the thread starts. 
    // It loops ten times, writing to the console and yielding  
    // the rest of its time slice each time, and then ends. 
    public static void ThreadProc() {
        for (int i = 0; i < 10; i++) {
            Console.WriteLine("ThreadProc: {0}", i);
            // Yield the rest of the time slice.
            Thread.Sleep(0);
        }
    }
    public static void Main() {
        Console.WriteLine("Main thread: Start a second thread.");
        // The constructor for the Thread class requires a ThreadStart  
        // delegate that represents the method to be executed on the  
        // thread.  C# simplifies the creation of this delegate.
        Thread t = new Thread(new ThreadStart(ThreadProc));
        // Start ThreadProc.  Note that on a uniprocessor, the new  
        // thread does not get any processor time until the main thread  
        // is preempted or yields.  Uncomment the Thread.Sleep that  
        // follows t.Start() to see the difference.
        t.Start();
        //Thread.Sleep(0); 
        for (int i = 0; i < 4; i++) {
            Console.WriteLine("Main thread: Do some work.");
            Thread.Sleep(0);
        }
        Console.WriteLine("Main thread: Call Join(), to wait until ThreadProc ends.");
        t.Join();
        Console.WriteLine("Main thread: ThreadProc.Join has returned.  Press Enter to end program.");
        Console.ReadLine();
    }
}
这个例子来自:http: //msdn.microsoft.com/en-us/library/system.threading.thread.aspx