delegate void DisplayStringDelegate(string str);

private void AppendString(string str)
{

if(this.Label1.InvokeRequird)
{
DisplayStringDelegate dd=new DisplayStringDelegate(AppendString);
this.Label1.Invoked(dd "abcdefg");
}
else
{
this.Label.Text+=str;
}
}

------解决方案--------------------

C# code
private delegate void Handler(); //可带参数..

private void Accessor() //注意: 参数列表, 要与 Handler 对应..
{
    if (this.InvokeRequired)
    {
        this.Invoke(new Handler(this.Accessor)); //如有参数, 在此传入..
    }
    else
    {
        lock (this)
        {
            //TODO: 在这里访问或处理..
        }
    }
}

private void Run()
{
    Thread thread = new Thread(new ThreadStart(this.Accessor));
    thread.Name = "访问控件";
    thread.IsBackground = true;
    thread.Start();
}

//
// 说明: 调用 Run 即可..
//