引用Word的Com组件Microsoft Word 11.0 Object Library,我的office2003的版本是8.3，默认安装的Office是没有这个组件的。用office盘，添加删除组件，选自定义，在Microsoft Office Word下面有.NET可编程性支持。安装。

引用到项目中Web.config多了这行

<compilation debug="false">
   <assemblies>
    <add assembly="Microsoft.Office.Interop.Word, Version=11.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c"/></assemblies>

程序代码:
        Microsoft.Office.Interop.Word.Application word = new Microsoft.Office.Interop.Word.ApplicationClass();
        //Word.ApplicationClass word = new Word.ApplicationClass();
        Type wordType = word.GetType();
        Microsoft.Office.Interop.Word.Documents docs = word.Documents;

// 打开文件
        Type docsType = docs.GetType();
        object fileName = "e:\\cc.doc";
        Microsoft.Office.Interop.Word.Document doc = (Microsoft.Office.Interop.Word.Document)docsType.InvokeMember("Open",
        System.Reflection.BindingFlags.InvokeMethod, null, (object)docs, new Object[] { fileName, true, true });

// 转换格式，另存为
        Type docType = doc.GetType();
        object saveFileName = "e:\\aaa.html";
        //下面是Microsoft Word 9(11.0) Object Library的写法，如果是10(没试过)，可能写成：
        /*
        docType.InvokeMember("SaveAs", System.Reflection.BindingFlags.InvokeMethod,
         null, doc, new object[]{saveFileName, Word.WdSaveFormat.wdFormatFilteredHTML});
        */
        ///其它格式：
        ///wdFormatHTML
        ///wdFormatDocument
        ///wdFormatDOSText
        ///wdFormatDOSTextLineBreaks
        ///wdFormatEncodedText
        ///wdFormatRTF
        ///wdFormatTemplate
        ///wdFormatText
        ///wdFormatTextLineBreaks
        ///wdFormatUnicodeText
        docType.InvokeMember("SaveAs", System.Reflection.BindingFlags.InvokeMethod,
         null, doc, new object[] { saveFileName, Microsoft.Office.Interop.Word.WdSaveFormat.wdFormatHTML });

// 退出 Word
        wordType.InvokeMember("Quit", System.Reflection.BindingFlags.InvokeMethod,
         null, word, null);