Word.Application wordApp = new Word.Application();
            object fileobj = docFileName;
            object nullobj = System.Reflection.Missing.Value;
            //打开指定文件（不同版本的COM参数个数有差异，一般而言除第一个外都用nullobj就行了）
            Word.Document doc = wordApp.Documents.Open(ref fileobj, ref nullobj, ref nullobj,
                ref nullobj, ref nullobj, ref nullobj,
                ref nullobj, ref nullobj, ref nullobj,
                ref nullobj, ref nullobj, ref nullobj, ref nullobj, ref nullobj, ref nullobj, ref nullobj
                );
            string strCase = string.Empty;
            foreach (Word.Bookmark BM in doc.Bookmarks)　　//这是最关键的地方：对文档的任何书签进行便利匹配
            {
                strCase = BM.Name.ToString();
                switch (strCase)
                {
                    case "E_ID":　//替换Advice书签的内容，其他相同
                        BM.Select();
                        BM.Range.Text = "asd";
                        break;
                }

using (MemoryStream mem = new MemoryStream())
            {
                // Create Document
                using (WordprocessingDocument wordDocument = WordprocessingDocument.Create(mem, 
          WordprocessingDocumentType.Document, true))
                {
                    // Add a main document part. 
                    MainDocumentPart mainPart = wordDocument.AddMainDocumentPart();

                    new Document(new Body()).Save(mainPart);

                    Body body = mainPart.Document.Body;
                    body.Append(new Paragraph(
                                new Run(
                                    new Text("Hello World!"))));

                    mainPart.Document.Save();
                    // Stream it down to the browser

                    // THIS IS PROBABLY THE CRUX OF THE MATTER <---
                    Response.AppendHeader("Content-Disposition", "attachment;filename=HelloWorld.docx");
                    Response.ContentType = "application/vnd.ms-word.document";
                    mem.WriteTo(Response.OutputStream);
                    Response.End();
                }

            }