1.定义ListItem类
public class ListItem
{
private string _key = string.Empty;
private string _value = string.Empty;
public ListItem(string pKey, string pValue)
{
_key = pKey;
_value = pValue;
}
public override string ToString()
{
return this._value;
}
public string Key
{
get
{
return this._key;
}
set
{
this._key = value;
}
}
public string Value
{
get
{
return this._value;
}
set
{
this._value = value;
}
}
}
2.使用
ListItem listItem1 = new ListItem("1","中国");
ListItem listItem2 = new ListItem("1","美国");
ListItem listItem3 = new ListItem("1","英国");
comboBox1.Items.Add(listItem1);
comboBox1.Items.Add(listItem2);
comboBox1.Items.Add(listItem3);
3.取值
string id = ((ListItem)comboBox1.SelectedItem).Key;
string value = ((ListItem)comboBox1.SelectedItem).Value;
4.默认选中项
comboBox1.SelectedIndex = 0;//设置第一项为默认选择项
comboBox1.SelectedItem = listItem1//设置指定的项为默认选择项
c#(winform)中自定义ListItem类方便ComboBox添加Item项
原文：http://www.cnblogs.com/lgx5/p/7214221.html