代码要是改进下就会实现下面的效果了:

            ListItem li = new ListItem("请选择网络组长", "0");
                    this.ddzz.Items.Insert(0, li);
                    ListItem li1 = new ListItem("网络一组组长", "4");
                    this.ddzz.Items.Insert(1, li1);

                    ListItem li2 = new ListItem("网络二组组长", "5");
                    this.ddzz.Items.Insert(2, li2);

                    ListItem li3 = new ListItem("网络新人组组长", "6");
                    this.ddzz.Items.Insert(3, li3);