http://www.cnblogs.com/cryf/articles/904004.html
Word.Application oWord;
Word.Document oDoc;
object name= "d:\\myfile.doc";
object Range=System.Reflection.Missing.Value;
object bookmarks="C2";oWord = new Word.ApplicationClass();
oWord.Visible = true;
//打开文档
oDoc = oWord.Documents.Open(ref name, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing);
oDoc.Bookmarks.get_Item(ref bookmarks).Select();
//插入图片 并设置图片大小
InlineShape il=oWord.Selection.InlineShapes.AddPicture("c:\\wjjpg.jpg", ref oMissing, ref oMissing, ref Range);
il.Width = 40;
il.Height = 50;