为了防止@leniel的链接中断，这里有一些代码可以做到这一点：

AutoCompleteStringCollection allowedTypes = new AutoCompleteStringCollection();
allowedTypes.AddRange(yourArrayOfSuggestions);
txtType.AutoCompleteCustomSource = allowedTypes;
txtType.AutoCompleteMode = AutoCompleteMode.Suggest;
txtType.AutoCompleteSource = AutoCompleteSource.CustomSource;

使用组合框代替文本框。下面的示例将自动完成，匹配文本的任何部分，而不仅仅是开始字母。
这应该是一个完整的表单，只需添加自己的数据源和数据源列名即可。：-）

using System;
using System.Data;
using System.Windows.Forms;

public partial class frmTestAutocomplete : Form
{

    private DataTable maoCompleteList;
    private const string MC_DISPLAY_COL = "name";
    private const string MC_ID_COL = "id";

    public frmTestAutocomplete()
    {
        InitializeComponent();
    }

    private void frmTestAutocomplete_Load(object sender, EventArgs e)
    {

        maoCompleteList = GetDataTableFromDatabase();
        maoCompleteList.CaseSensitive = false; //turn off case sensitivity for searching

        testCombo.DisplayMember = MC_DISPLAY_COL;
        testCombo.ValueMember = MC_ID_COL;
        testCombo.DataSource = maoCompleteList;
        testCombo.SelectedIndexChanged += testCombo_SelectedIndexChanged;
        testCombo.KeyUp += testCombo_KeyUp;
    }

    private void testCombo_KeyUp(object sender, KeyEventArgs e)
    {
        //use keyUp event, as text changed traps too many other evengts.

        ComboBox oBox = (ComboBox)sender;
        string sBoxText = oBox.Text;

        DataRow[] oFilteredRows = maoCompleteList.Select(MC_DISPLAY_COL + " Like '%" + sBoxText + "%'");

        DataTable oFilteredDT = oFilteredRows.Length > 0
                                ? oFilteredRows.CopyToDataTable()
                                : maoCompleteList;

        //NOW THAT WE HAVE OUR FILTERED LIST, WE NEED TO RE-BIND IT WIHOUT CHANGING THE TEXT IN THE ComboBox.

        //1).UNREGISTER THE SELECTED EVENT BEFORE RE-BINDING, b/c IT TRIGGERS ON BIND.
        oBox.SelectedIndexChanged -= testCombo_SelectedIndexChanged; //don't select on typing.
        oBox.DataSource = oFilteredDT; //2).rebind to filtered list.
        oBox.SelectedIndexChanged += testCombo_SelectedIndexChanged;

        //3).show the user the new filtered list.
        oBox.DroppedDown = true; //this will overwrite the text in the ComboBox, so 4&5 put it back.

        //4).binding data source erases text, so now we need to put the user's text back,
        oBox.Text = sBoxText;
        oBox.SelectionStart = sBoxText.Length; //5). need to put the user's cursor back where it was.

    }

    private void testCombo_SelectedIndexChanged(object sender, EventArgs e)
    {

        ComboBox oBox = (ComboBox)sender;

        if (oBox.SelectedValue != null)
        {
            MessageBox.Show(string.Format(@"Item #{0} was selected.", oBox.SelectedValue));
        }
    }

}

//=====================================================================================================
//      code from frmTestAutocomplete.Designer.cs
//=====================================================================================================
partial class frmTestAutocomplete

{
    /// <summary>
    /// Required designer variable.
    /// </summary>
    private readonly System.ComponentModel.IContainer components = null;

    /// <summary>
    /// Clean up any resources being used.
    /// </summary>
    /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
    protected override void Dispose(bool disposing)
    {
        if (disposing && (components != null))
        {
            components.Dispose();
        }
        base.Dispose(disposing);
    }

    #region Windows Form Designer generated code

    /// <summary>
    /// Required method for Designer support - do not modify
    /// the contents of this method with the code editor.
    /// </summary>
    private void InitializeComponent()
    {
        this.testCombo = new System.Windows.Forms.ComboBox();
        this.SuspendLayout();
        // 
        // testCombo
        // 
        this.testCombo.FormattingEnabled = true;
        this.testCombo.Location = new System.Drawing.Point(27, 51);
        this.testCombo.Name = "testCombo";
        this.testCombo.Size = new System.Drawing.Size(224, 21);
        this.testCombo.TabIndex = 0;
        // 
        // frmTestAutocomplete
        // 
        this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
        this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
        this.ClientSize = new System.Drawing.Size(292, 273);
        this.Controls.Add(this.testCombo);
        this.Name = "frmTestAutocomplete";
        this.Text = "frmTestAutocomplete";
        this.Load += new System.EventHandler(this.frmTestAutocomplete_Load);
        this.ResumeLayout(false);

    }

    #endregion

    private System.Windows.Forms.ComboBox testCombo;
}

Leniel的答案链接在www.example.com中vb.net，感谢Joel的参与。提供我的代码以使其更明确：

private void InitializeTextBox()
{

    AutoCompleteStringCollection allowedStatorTypes = new AutoCompleteStringCollection();
    var allstatortypes = StatorTypeDAL.LoadList<List<StatorType>>().OrderBy(x => x.Name).Select(x => x.Name).Distinct().ToList();

    if (allstatortypes != null && allstatortypes.Count > 0)
    {
        foreach (string item in allstatortypes)
        {
            allowedStatorTypes.Add(item);
        }
    }

    txtStatorTypes.AutoCompleteMode = AutoCompleteMode.Suggest;
    txtStatorTypes.AutoCompleteSource = AutoCompleteSource.CustomSource;
    txtStatorTypes.AutoCompleteCustomSource = allowedStatorTypes;
}

使用组合框，设置其数据源或给予硬编码条目，但设置以下属性：

AutoCompleteMode = Suggest;
    AutoCompleteSource = ListItems;

你想把TextBox.AutoCompleteSource设置为CustomSource，然后把所有的字符串添加到它的AutoCompleteCustomSource属性，也就是StringCollection，然后你就可以开始了。

我想补充的是，TextBox的标准自动完成功能只能从字符串的开头开始工作，因此如果您点击N，则只能找到以N开头的字符串。如果您希望有更好的功能，则必须使用其他控件或自己实现该行为（即用一些定时器对TextChanged事件作出React以延迟执行，然后使用IndexOf（inputString）过滤标记列表搜索，然后将AutoCompleteSource设置为过滤后的列表。