public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    public static void WordToHtmlRtf(string WordFilePath)
    {
        try
        {
            Microsoft.Office.Interop.Word.Application wApp = new Microsoft.Office.Interop.Word.Application();
            //指定原文件和目標文件 
            object docPath = WordFilePath;
            string htmlPath;
            if (WordFilePath.Contains(".docx"))
            {
                htmlPath = WordFilePath.Substring(0, WordFilePath.Length - 4) + "rtf";
            }
            else
            {
                htmlPath = WordFilePath.Substring(0, WordFilePath.Length - 3) + "rtf";
            }

            object Target = htmlPath;
            //缺省參數 
            object Unknown = Type.Missing;
            //只讀方式打開 
            object readOnly = true;
            //打開doc文件 
            Microsoft.Office.Interop.Word.Document document = wApp.Documents.Open(ref docPath, ref Unknown,
                ref readOnly, ref Unknown, ref Unknown,
                ref Unknown, ref Unknown, ref Unknown,
                ref Unknown, ref Unknown, ref Unknown,
                ref Unknown);
            // 指定格式
            object format = Microsoft.Office.Interop.Word.WdSaveFormat.wdFormatRTF;
            // 轉換格式 
            document.SaveAs(ref Target, ref format,
                ref Unknown, ref Unknown, ref Unknown,
                ref Unknown, ref Unknown, ref Unknown,
                ref Unknown, ref Unknown, ref Unknown);
            // 關閉文檔和Word程序 
            document.Close(ref Unknown, ref Unknown, ref Unknown);
            wApp.Quit(ref Unknown, ref Unknown, ref Unknown);
        }
        catch (Exception e)
        {
            MessageBox.Show(e.Message);
        }
    }

    private void Form1_Load(object sender, EventArgs e)
    {
    }

    private void button1_Click(object sender, EventArgs e)
    {
        if (openFileDialog1.ShowDialog() == DialogResult.OK)
            textBox1.Text = openFileDialog1.FileName;
    }

    private void button2_Click(object sender, EventArgs e)
    {
        if (textBox1.Text != "")
        {
            WordToHtmlRtf(textBox1.Text.Trim());
            MessageBox.Show("轉換成功，保存在Word文件的同目錄下！");
        }
    }
}

partial class Form1
{
    /// <summary>
    /// 必需的設計器變量。
    /// </summary>
    private System.ComponentModel.IContainer components = null;

    /// <summary>
    /// 清理所有正在使用的資源。
    /// </summary>
    /// <param name="disposing">如果應釋放托管資源，為 true；否則為 false。</param>
    protected override void Dispose(bool disposing)
    {
        if (disposing && (components != null))
        {
            components.Dispose();
        }
        base.Dispose(disposing);
    }

    #region Windows 窗體設計器生成的代碼

    /// <summary>
    /// 設計器支持所需的方法 - 不要
    /// 使用代碼編輯器修改此方法的內容。
    /// </summary>
    private void InitializeComponent()
    {
        this.button1 = new System.Windows.Forms.Button();
        this.label1 = new System.Windows.Forms.Label();
        this.textBox1 = new System.Windows.Forms.TextBox();
        this.button2 = new System.Windows.Forms.Button();
        this.openFileDialog1 = new System.Windows.Forms.OpenFileDialog();
        this.SuspendLayout();
        // 
        // button1
        // 
        this.button1.Location = new System.Drawing.Point(307, 19);
        this.button1.Name = "button1";
        this.button1.Size = new System.Drawing.Size(75, 23);
        this.button1.TabIndex = 0;
        this.button1.Text = "瀏覽";
        this.button1.UseVisualStyleBackColor = true;
        this.button1.Click += new System.EventHandler(this.button1_Click);
        // 
        // label1
        // 
        this.label1.AutoSize = true;
        this.label1.Location = new System.Drawing.Point(12, 24);
        this.label1.Name = "label1";
        this.label1.Size = new System.Drawing.Size(77, 12);
        this.label1.TabIndex = 1;
        this.label1.Text = "選擇Word文檔";
        // 
        // textBox1
        // 
        this.textBox1.Enabled = false;
        this.textBox1.Location = new System.Drawing.Point(95, 21);
        this.textBox1.Name = "textBox1";
        this.textBox1.Size = new System.Drawing.Size(206, 21);
        this.textBox1.TabIndex = 2;
        // 
        // button2
        // 
        this.button2.Location = new System.Drawing.Point(155, 48);
        this.button2.Name = "button2";
        this.button2.Size = new System.Drawing.Size(75, 23);
        this.button2.TabIndex = 3;
        this.button2.Text = "轉換";
        this.button2.UseVisualStyleBackColor = true;
        this.button2.Click += new System.EventHandler(this.button2_Click);
        // 
        // openFileDialog1
        // 
        this.openFileDialog1.Filter = "Word文檔|*.doc|Word文檔|*.docx";
        // 
        // Form1
        // 
        this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);
        this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
        this.ClientSize = new System.Drawing.Size(402, 80);
        this.Controls.Add(this.button2);
        this.Controls.Add(this.textBox1);
        this.Controls.Add(this.label1);
        this.Controls.Add(this.button1);
        this.Name = "Form1";
        this.Text = "Form1";
        this.Load += new System.EventHandler(this.Form1_Load);
        this.ResumeLayout(false);
        this.PerformLayout();

    }

    #endregion

    private System.Windows.Forms.Button button1;
    private System.Windows.Forms.Label label1;
    private System.Windows.Forms.TextBox textBox1;
    private System.Windows.Forms.Button button2;
    private System.Windows.Forms.OpenFileDialog openFileDialog1;
}