首先引用ThoughtWorks.QRCode.dll

代码：

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Drawing;using ThoughtWorks.QRCode.Codec;namespace QRCodeUtil{    /// 
    /// 二维码生成    /// 
    public class QRCodeHelper    {        #region 根据链接获取二维码        /// 
        /// 根据链接获取二维码        /// 
        /// 链接        /// 
      
       返回二维码图片
              public static Bitmap GetQRCodeBmp(string link)        {            QRCodeEncoder qrCodeEncoder = new QRCodeEncoder();            qrCodeEncoder.QRCodeEncodeMode = QRCodeEncoder.ENCODE_MODE.BYTE;            qrCodeEncoder.QRCodeScale = 4;            qrCodeEncoder.QRCodeVersion = 0;            qrCodeEncoder.QRCodeErrorCorrect = QRCodeEncoder.ERROR_CORRECTION.M;            Bitmap bmp = qrCodeEncoder.Encode(link);            return bmp;        }        #endregion    }}

使用示例：

using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;using System.Drawing;using QRCodeUtil;namespace SWX{    public partial class WebForm1 : System.Web.UI.Page    {        protected void Page_Load(object sender, EventArgs e)        {            Bitmap bmp = QRCodeHelper.GetQRCodeBmp(@"http://www.baidu.com/");            string str = HttpContext.Current.Request.MapPath("\\aa.bmp");            bmp.Save(str);        }    }}