Aiming at the problem of the navigation information on Baidu map being not perfect in campus, an Android mobile navigation system is designed and implemented through setting up net database. The overall architecture of the system and the client software structure are introduced firstly. Then this paper discusses emphatically the design of function modules, including client interface, route navigation module, campus building navigation module and indoor scene module. The system has two distinct characteristics, which are embodied in the hierarchical software architecture, and in the combination of Baidu maps and self-build database. With the comparison between our system and Baidu map, the experimental results show that our system is able to navigate the missing common building in the campus of Baidu maps successfully. All in all, our system has the advantages of simple operation, stable operation, high user experience, maintainability and strong practical value.