繫結資料來源：

   private void button2_Click(object sender, EventArgs e)
        {
            DataTable table = new DataTable();
            DataColumn column;
            DataRow row;
            column = new DataColumn("Name");
            table.Columns.Add(column);
            column = new DataColumn("Value");
            table.Columns.Add(column);
            row = table.NewRow();
            row["Name"] = "1";
            row["Value"] = "張三";
            table.Rows.Add(row);
            row = table.NewRow();
            row["Name"] = "2";
            row["Value"] = "李四";
            table.Rows.Add(row);
            //呼叫comboBox1_SelectedValueChanged(
            //comboBox1.DataSource = table;
            //comboBox1.DisplayMember = "Name";
            //comboBox1.ValueMember = "Value"; 

            //呼叫comboBox1_SelectedIndexChanged
            comboBox1.DisplayMember = "Name";
            comboBox1.ValueMember = "Value";
            comboBox1.DataSource = table;


        }

        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
              textBox1.Text= comboBox1.SelectedValue.ToString();
        }

        private void comboBox1_SelectedValueChanged(object sender, EventArgs e)
        {
              //textBox1.Text= comboBox1.SelectedValue.ToString();
        }
 

當使用SelectedIndexChanged時，ValueMember在DataSource前進行賦值，當使用SelectedValueChanged時，ValueMember在DataSource後進行賦值。

下拉樣式：

           //comboBox1.DropDownStyle = ComboBoxStyle.DropDownList;//不允許輸入的下拉框
            comboBox1.DropDownStyle = ComboBoxStyle.DropDown;//允許輸入的下拉框

            comboBox1.Items.Add("1");
            comboBox1.Items.Add("2");
            comboBox1.Items.Add("3");
            comboBox1.Items.Add("4");
            comboBox1.Items.Add("5");
            comboBox1.Items.Add("6");
 

            comboBox1.SelectedIndex = 0;//設定預設值
            //comboBox1.Text = "1";//這樣也可以設定預設值

   //刪除指定元素
            //comboBox1.Items.Remove("1");

            //通過索引刪除制定元素
            //comboBox1.Items.RemoveAt(0);
            //comboBox1.Items.RemoveAt(comboBox1.Items.IndexOf("1"));

            //刪除所有元素
            comboBox1.Items.Clear();
            comboBox1.Text = "";
 

        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
              textBox1.Text = comboBox1.SelectedItem.ToString();
        }