protected void Button1_Click(object sender, EventArgs e)
{
 string[] srr = { "one", "thr" };
 foreach (string item in srr)
 {
 for (int intItem = 0; intItem <= ListBox1.Items.Count - 1; intItem++) {
      if(ListBox1.Items(intItem).Text == item){
            ListBox1.Items(intItem).Selected = true;
      }
    }
}

检查每个项目的选定属性.看一下此链接上的示例:
http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.listcontrol.items.aspx [

Check the selected property of each item. Have a look at the example at this link:
http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.listcontrol.items.aspx[^]

Good luck!