1 public Form1()
 2         {
 3             InitializeComponent();
 4         }
 5 
 6         private void Form1_Load(object sender, EventArgs e)
 7         {
 8             Form2 f2 = new Form2(this);
 9             f2.Show();
10         }

 1 Form1 f1;
 2         public Form2( Form1 f11)
 3         {
 4             InitializeComponent();
 5             f1 = f11;
 6         }
 7 
 8         private void button1_Click(object sender, EventArgs e)
 9         {
10             f1.button1.Text = "这是F2点击的";
11         }