this.comboBox1.DrawMode = DrawMode.OwnerDrawFixed;

            this.comboBox1.DrawItem += new DrawItemEventHandler(comboBox1_DrawItem);
        }

        void comboBox1_DrawItem(object sender, DrawItemEventArgs e)
        {
            string txt = this.comboBox1.Items[e.Index].ToString();
            Graphics g = e.Graphics;
            Font f = new Font("宋体", 9);
            if (e.State == DrawItemState.Selected)
            {
                this.label2.Text = txt;
                g.FillRectangle(Brushes.Blue, 0, e.Index * 15, this.comboBox1.Width, 12);
                g.DrawString(txt, f, Brushes.White, 0, e.Index * 15);
            }
            else
            {
                g.FillRectangle(Brushes.White, 0, e.Index * 15, this.comboBox1.Width, 12);
                g.DrawString(txt, f, Brushes.Black, 0, e.Index * 15);
            }
        }