如果我理解你的问题:
 - Form2 有 2 个文本框(textBox1和textBox2)和 2 个按钮(btnOK和btnCancel)
 - 如果btnOK按下 - 连接和的值textBox1并将textBox2它们传递给Form1
 - 如果btnCancel按下 - 不传递任何数据  
我的答案的简要描述:
 它可以通过事件处理程序轻松实现,只需连接到OnFormClosing事件并从预定义的属性中读取数据Form2
下面是一些说明我的答案的代码
Form1.cs
public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        private void button1_Click(object sender, EventArgs e)
        {
            Form2 frm2 = new Form2();
            frm2.Show();
            frm2.FormClosing += new FormClosingEventHandler(frm2_FormClosing);
        }
        void frm2_FormClosing(object sender, FormClosingEventArgs e)
        {
            if ((sender as Form2).textData != null)
                textBox1.Text = (sender as Form2).textData;
        }
    }
Form2.cs
 public partial class Form2 : Form
    {
        public string textData;
        public Form2()
        {
            InitializeComponent();
        }
        private void btnOK_Click(object sender, EventArgs e)
        {
            textData = textBox1.Text + " " + textBox2.Text;
            this.Close();
        }
        private void btnCancel_Click(object sender, EventArgs e)
        {
            this.Close();
        }
    }