[PublishEvent("OnSearch")]
        public event EventHandler<DataEventArgs<string>> OnSearchEvent;
    private void txtSearch_KeyUp(object sender, KeyEventArgs e)
        {
            if (OnSearchEvent != null)
            {
                // Raise the event and notify the controller
                OnSearchEvent(this, new DataEventArgs<string>(txtSearch.Text));
            }  
        }

     // Search event from the view
        private void OnSearch(object sender, DataEventArgs<string> e)
      {
            // 1、更新数据集合代码
            // 2、更新界面
       }

------解决方案--------------------
this.comboBox1.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
this.comboBox1.AutoCompleteSource = AutoCompleteSource.ListItems;

------解决方案--------------------
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;  

namespace Combobox_实现数据库模糊查询动态绑定
{
   public partial class Form1 : Form
   {
       public Form1()
       {
           InitializeComponent();
       }
       static string SqlConnectionString = @"Data Source=.\SQLEXPRESS;AttachDbFilename=D:\C#项目文件\Database\MyPersonnel.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True";  
       SqlConnection conn = new SqlConnection(SqlConnectionString);
       bool isover = false;
       private void comboBox1_TextChanged(object sender, EventArgs e)
       {
           if (!isover)
           {
               string comboboxtext = this.comboBox1.Text.Trim();
               string str = "SELECT 省份 FROM 省份信息 WHERE 省份 LIKE " + "'" + this.comboBox1.Text.Trim() + "%'";
               SqlCommand comm = new SqlCommand(str, conn);
               if (conn.State == ConnectionState.Closed)
               {
                   conn.Open();
               }
               SqlDataAdapter dataAdapter = new SqlDataAdapter(comm);
               DataSet ds = new DataSet();               
               dataAdapter.Fill(ds);
               List<string> shengfen = new List<string>();
               foreach (DataRow row in ds.Tables[0].Rows)
               {
                   foreach (DataColumn column in ds.Tables[0].Columns)
                   {
                       shengfen.Add(row[column].ToString());
                   }
               }
               int index=0;
               for (int i = 0; i < shengfen.Count; i++)
               {
                   if (shengfen[i] == comboboxtext)
                   {
                       index = i;
                       isover = true;
                   }
               }
               this.comboBox1.DataSource = shengfen;
               this.comboBox1.SelectedIndex = index ;
               this.comboBox1.DropDownStyle = ComboBoxStyle.DropDown;
           }
           else
           {
           }
       }
   }
}

可能还有些小问题,自己改下.

------解决方案--------------------