思路：通过在Word中设置书签 ，调用Word的方法去查找书签然后进行替换保存。
代码如下：
首先添加OFFCIE引用
Microsoft Office 15.0 Object Library 这个直接通过COM添加
Microsoft.Office.Interop.Word.dll 这个DLL 在 C:\Program Files (x86)\Microsoft Visual Studio 10.0\Visual Studio Tools for Office\PIA下 也就是你的VS 安装目录下面。
public void SignProduct() { object Nothing = System.Reflection.Missing.Value; //创建一个名为wordApp的组件对象 Application wordApp = new Application(); //word文档位置 object filename = @"E:\2013.08.29需求说明书 V1.2.doc"; //定义该插入图片是否为外部链接 object linkToFile = true; //定义插入图片是否随word文档一起保存 object saveWithDocument = true; //打开word文档 Microsoft.Office.Interop.Word.Document doc = wordApp.Documents.Open(ref filename, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing); try { //标签 object bookMark = "mark1"; //图片 string replacePic = @"E:\1.gif"; if (doc.Bookmarks.Exists(Convert.ToString(bookMark)) == true) { //查找书签 doc.Bookmarks.get_Item(ref bookMark).Select(); //设置图片位置 wordApp.Selection.ParagraphFormat.Alignment = Microsoft.Office.Interop.Word.WdParagraphAlignment.wdAlignParagraphRight; //在书签的位置添加图片 InlineShape inlineShape = wordApp.Selection.InlineShapes.AddPicture(replacePic, ref linkToFile, ref saveWithDocument, ref Nothing); //设置图片大小 inlineShape.Width = 80; inlineShape.Height = 20; doc.Save(); } else { //word文档中不存在该书签，关闭文档 doc.Close(ref Nothing, ref Nothing, ref Nothing); } } catch { doc.Close(ref Nothing, ref Nothing, ref Nothing); } }