IList<string> list = new List<string>();
list.Add("111111");
list.Add("222222");
list.Add("333333");
list.Add("444444");
comboBox1.DataSource = list;

public class Info
{
  public string Id { get; set; }
  public string Name { get; set; }
}
private void bindCbox()
{
  IList<Info> infoList = new List<Info>();
  Info info1 = new Info() { Id="1",Name="张三"};
  Info info2 = new Info() { Id="2",Name="李四"};
  Info info3 = new Info() { Id = "3",Name = "王五" };
  infoList.Add(info1);
  infoList.Add(info2);
  infoList.Add(info3);
  comboBox1.DataSource = infoList;
  comboBox1.ValueMember = "Id";
  comboBox1.DisplayMember = "Name";
}

Dictionary<int, string> kvDictonary = new Dictionary<int, string>();
kvDictonary.Add(1, "11111");
kvDictonary.Add(2, "22222");
kvDictonary.Add(3, "333333");
BindingSource bs = new BindingSource();
bs.DataSource = kvDictonary;
comboBox1.DataSource = bs;
comboBox1.ValueMember = "Key";
comboBox1.DisplayMember = "Value";

//数据集绑定
private void BindCombox()
{
  DataTable dt = new DataTable();
  DataColumn dc1 = new DataColumn("id");
  DataColumn dc2 = new DataColumn("name");
  dt.Columns.Add(dc1);
  dt.Columns.Add(dc2);
  DataRow dr1 = dt.NewRow();
  dr1["id"] = "1";
  dr1["name"] = "aaaaaa";
  DataRow dr2 = dt.NewRow();
  dr2["id"] = "2";
  dr2["name"] = "bbbbbb";
  dt.Rows.Add(dr1);
  dt.Rows.Add(dr2);
  comboBox1.DataSource = dt;
  comboBox1.ValueMember = "id";
  comboBox1.DisplayMember = "name";
}

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
  if(this.fig)
  {
    string selectValue = this.cmbAddMember.SelectedValue.ToString();
    rtbaddMember.SelectedText = selectValue;
  }
}

private void SetAutoMessage_Load(object sender, EventArgs e)
{
  loadCombox();
  loadMessageTemplet();
  fig= true;
}