C#Winform省市联动下拉框

//定义字典
Dictionary<string, string> Address = new Dictionary<string, string>();

        void loadData()
        {
           //这是你要添加的数据
          //也可以选择动态添加但是考虑到数据不多不影响性能就这么做了
            Address.Add("绵阳", "四川");
            Address.Add("成都", "四川");
            Address.Add("广汉", "四川");
            Address.Add("南京", "江苏");
            Address.Add("扬州", "江苏");
            Address.Add("无锡", "江苏");
            Address.Add("珠海", "广州");
            Address.Add("东莞", "广州");
            Address.Add("深圳", "广州");
            Address.Add("上海", "直辖市");

            //通过循环值添加进省会下拉框
            foreach (string province in Address.Values)
            { 
                 //判断下 避免重复添加省会名
                if (!comboBoxEdit1.Properties.Items.Contains(province))
                    comboBoxEdit1.Properties.Items.Add(province);
            }

//省会下拉框选择索引方法
private void comboBoxEdit1_SelectedIndexChanged(object sender, EventArgs e)
        {
            //添加之前先把市级下拉框清空 避免追加数据 
            //你也可以选择动态添加
            comboBoxEdit2.Properties.Items.Clear();
           //通过值查找键值
            foreach (KeyValuePair<string, string> kvp in Address)
            {
                if (kvp.Value.Equals(comboBoxEdit1.SelectedItem.ToString()))
                {
                    comboBoxEdit2.Properties.Items.Add(kvp.Key);
                }
            }        
        }