当从浏览器返回一个文件时,需要指定ContentType,以下是Office2007对应的值:
"application/vnd.openxmlformats-officedocument.wordprocessingml.template" (for .dotx files)
"application/vnd.openxmlformats-officedocument.presentationml.presentation" (for .pptx files)
"application/vnd.openxmlformats-officedocument.presentationml.slideshow" (for .ppsx files)
"application/vnd.openxmlformats-officedocument.presentationml.template" (for .potx files)
"application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" (for .xlsx files)
"application/vnd.openxmlformats-officedocument.spreadsheetml.template" (for .xltx files)
相对于Office2003是这样的
Response.ContentType = "application/vnd.ms-excel"
‘Excel 2003 : "application/vnd.ms-excel"
‘Excel 2007 : "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
Microsoft Office 2007的ContentType
原文：http://www.cnblogs.com/zwei1121/p/4025597.html