public static void WordToRtf(string file_Name, string file_Wname) 

    {

        //创建一个word的实例

        Word.Application newApp = new Word.Application();

        // 指定源文件和目标文件

        object Source = file_Wname;

        object Target = file_Name;

        object Unknown = Type.Missing;

        newApp.Documents.Open(ref Source, ref Unknown, ref Unknown, ref Unknown, ref Unknown, ref Unknown, ref Unknown, ref Unknown, ref Unknown, ref Unknown, ref Unknown, ref Unknown, ref Unknown, ref Unknown, ref Unknown, ref Unknown);

        // 指定文档的类型

        object format = Word.WdSaveFormat.wdFormatRTF;



        //改变文档类型,这个函数参数会因为word版本的不同而不同，我的是word 10

        newApp.ActiveDocument.SaveAs(ref Target, ref format,

         ref Unknown, ref Unknown, ref Unknown,

         ref Unknown, ref Unknown, ref Unknown,

         ref Unknown, ref Unknown, ref Unknown, ref Unknown,

         ref Unknown, ref Unknown, ref Unknown, ref Unknown);



        newApp.Visible = false;



        //关闭word实例

        newApp.Documents.Close(ref Unknown, ref Unknown, ref Unknown);

        newApp.Quit(ref Unknown, ref Unknown, ref Unknown);

        newApp = null;

    

    }