ThoughtWorks.QRCode.Codec.QRCodeEncoder encoder = new QRCodeEncoder();
        encoder.QRCodeEncodeMode = QRCodeEncoder.ENCODE_MODE.BYTE;//编码方法(注意：BYTE能支持中文，ALPHA_NUMERIC扫描出来的都是数字)
        encoder.QRCodeScale = 4;//大小
        encoder.QRCodeVersion = 0;//版本(注意：设置为0主要是防止编码的字符串太长时发生错误)
         encoder.QRCodeErrorCorrect = QRCodeEncoder.ERROR_CORRECTION.M;
  String qrdata = "二维码信息";
System.Drawing.Bitmap bp = encoder.Encode(qrdata.ToString(), Encoding.GetEncoding("GB2312"));
            Image image = bp;
            Object oMissing = System.Reflection.Missing.Value;
            pictureBox1.Image = bp;
保存二维码图片：
SaveFileDialog sf = new SaveFileDialog();
            sf.Title = "选择保存文件位置";
            sf.Filter = "保存图片(*.jpg) |*.jpg|所有文件(*.*) |*.*";
            //设置默认文件类型显示顺序
            sf.FilterIndex = 1;
            //保存对话框是否记忆上次打开的目录
            sf.RestoreDirectory = true;
            if (sf.ShowDialog() == DialogResult.OK)
            {
                Image im = this.pictureBox1.Image;
                //获得文件路径
                string localFilePath = sf.FileName.ToString();
                if (sf.FileName != "")
                {
                    string fileNameExt = localFilePath.Substring(localFilePath.LastIndexOf("\\") + 1);//获取文件名，不带路径
                   // newFileName = fileNameExt+DateTime.Now.ToString("yyyyMMdd")  ;//给文件名后加上时间
                   string FilePath = localFilePath.Substring(0, localFilePath.LastIndexOf("."));  //获取文件路径，带文件名,不带后缀
                    string fn = sf.FileName;
                    pictureBox1.Image.Save(FilePath +"-"+ DateTime.Now.ToString("yyyyMMdd") + ".jpg");
                   
                }
}
  //解析二维码信息
  // QRCodeDecoder decoder = new QRCodeDecoder();
  //  String decodedString = decoder.decode(new QRCodeBitmapImage(new Bitmap(pictureBox1.Image)));
   //this.label3.Text = decodedString; 

2、另一种方法，引用ZXing类库。
  ZXing是一个开源Java类库用于解析多种格式的1D/2D条形码。目标是能够对QR编码、Data Matrix、UPC的1D条形码进行解码。于此同时，它同样提供 cpp，ActionScript，android，iPhone，rim，j2me，j2se，jruby，C#等方式的类库。zxing类库的作用主 要是解码，是目前开源类库中解码能力比较强的（商业的另说，不过对于动辄成千上万的类库授权费用，的确很值）。

到谷歌code下载相应的代码
1.下载zxing最新的包
到zxing的主页： http://code.google.com/p/zxing/
找到其中的CSharp文件夹，在vs中打开并编译，将obj下debug中的zxing.dll复制并粘帖到你的项目中的bin文件目录下，

右击添加项目引用。将zxing.dll引用到项目中，就可以在需要的地方使用了。
源代码中有两处UTF-8的问题，会导致中文出现乱码（编译.dll之前修改）
其一：com.google.zxing.qrcode.encoder.encoder类中的
internal const System.String DEFAULT_BYTE_MODE_ENCODING = "ISO-8859-1";
此处，将ISO-8859-1改为UTF-8
其二：com.google.zxing.qrcode.decoder.DecodedBitStreamParser类的成员
private const System.String UTF8 = "UTF8";
应将UTF8改为UTF-8

生成代码：
//引用
 using com.google.zxing.qrcode;
  using com.google.zxing;
  using com.google.zxing.common;
  using ByteMatrix = com.google.zxing.common.ByteMatrix;
  using EAN13Writer = com.google.zxing.oned.EAN13Writer;
  using EAN8Writer = com.google.zxing.oned.EAN8Writer;
  using MultiFormatWriter = com.google.zxing.MultiFormatWriter;
        方法：
       string content = "二维码信息";
        ByteMatrix byteMatrix = new MultiFormatWriter().encode(content, BarcodeFormat.QR_CODE, 300, 300);
        Bitmap bitmap = toBitmap(byteMatrix);
        pictureBox1.Image = bitmap;
        SaveFileDialog sFD = new SaveFileDialog();
        sFD.Filter = "保存图片(*.png) |*.png|所有文件(*.*) |*.*";
        sFD.DefaultExt = "*.png|*.png";
        sFD.AddExtension = true;
        if (sFD.ShowDialog() == DialogResult.OK)
        {
            if (sFD.FileName != "")
            {
                writeToFile(byteMatrix, System.Drawing.Imaging.ImageFormat.Png, sFD.FileName);
            }

        }
解析：
    if (this.openFileDialog1.ShowDialog() != DialogResult.OK)
        {
            return;
        }
        Image img = Image.FromFile(this.openFileDialog1.FileName);
        Bitmap bmap;
        try
        {
            bmap = new Bitmap(img);
        }
        catch (System.IO.IOException ioe)
        {
            MessageBox.Show(ioe.ToString());
            return;
        }
        if (bmap == null)
        {
            MessageBox.Show("Could not decode image");
            return;
        }
        LuminanceSource source = new RGBLuminanceSource(bmap, bmap.Width, bmap.Height);
        com.google.zxing.BinaryBitmap bitmap1 = new com.google.zxing.BinaryBitmap(new HybridBinarizer(source));
        Result result;
        try
        {
            result = new MultiFormatReader().decode(bitmap1);
        }
        catch (ReaderException re)
        {
            MessageBox.Show(re.ToString());
            return;
        }

        MessageBox.Show(result.Text); 

  public static void writeToFile(ByteMatrix matrix, System.Drawing.Imaging.ImageFormat format, string file)
    {
        Bitmap bmap = toBitmap(matrix);
        bmap.Save(file, format);
    }

    public static Bitmap toBitmap(ByteMatrix matrix)
    {
        int width = matrix.Width;
        int height = matrix.Height;
        Bitmap bmap = new Bitmap(width, height, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
        for (int x = 0; x < width; x++)
        {
            for (int y = 0; y < height; y++)
            {
                bmap.SetPixel(x, y, matrix.get_Renamed(x, y) != -1 ? ColorTranslator.FromHtml("0xFF000000") : ColorTranslator.FromHtml("0xFFFFFFFF"));
            }
        }
        return bmap;
    }