效果图：

1.新建实体类：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace hsBankZjdzManager.Entity
{/// <summary>/// 下拉框赋值模板/// </summary>public class ComBoxData{public string key { get; set; }public string value { get; set; }}
}

2.赋值：

/// <summary>
/// 下拉框赋值
/// </summary>
private void setComBoxValue()
{List<TBankInfo> listBankInfo = receivingBankFormSQL.selectData("");// 初始化下拉框List<ComBoxData> list = new List<ComBoxData>();foreach (var item in listBankInfo){ComBoxData comBoxData = new ComBoxData();comBoxData.key = item.fName;comBoxData.value = item.fId+"";list.Add(comBoxData);}            comboBox1.DataSource = list;comboBox1.DisplayMember = "key";comboBox1.ValueMember = "value";// 默认显示第一个this.comboBox1.SelectedIndex = 0;
}

3.取值：

// 获取ValueMember值
string str = comboBox1.SelectedValue + "";
// 获取索引
string str1 = comboBox1.SelectedIndex + "";
// 获取DisplayMember值
string str2 = comboBox1.Text;