The invention aims to disclose a web desktop mode based inner-enterprise unified office platform system which is simple, safe and efficient in inner-enterprise business system access. The web desktop mode based inner-enterprise unified office platform system comprises a Web desktop, a supporting system and business systems. The Web desktop displays traditional menu-type and navigation-type functions by icons through an HTML5 (hypertext markup language 5) framework technology, and corresponding office functions and the corresponding business systems can be started by clicking the desktop icons. The supporting system comprises a file storage system and a 4A authentication system, wherein the file storage system is used for unified file storage, and the 4A authentication system is used for achieving unified management, authorization, authentication and audit functions of an account. The required business systems access to the 4A authentication system to achieve unified management. The web desktop mode based inner-enterprise unified office platform system is applicable to unified management of all inner-enterprise business systems.