public class ComboBoxItem
        {
            private string _text = null;
            private object _value = null;
            public string Text { get { return this._text; } set { this._text = value; } }
            public object Value { get { return this._value; } set { this._value = value; } }
            public override string ToString()
            {
                return this._text;
            }
        }

//使用时代码
private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (comboBox1.Items != null && comboBox1.Items.Count > 0 && comboBox1.SelectedItem != null)
            {
                string text = ((ComboBoxItem)comboBox1.SelectedItem).Text;
                object vlaue = ((ComboBoxItem)comboBox1.SelectedItem).Value;
            }
        }