When we look for books in the library, we often spend a lot of time looking for bookcases and book locations. In order to solve this problem, this study implements a set of APPs for library search services. Combining the actual and virtual functions of augmented reality, a mobile application of a book finding system is developed. Then the system is used to help a user find a book efficiently. An experiment is conducted to evaluated the performance of the system. There are several findings. First, a bookcase is found more efficient by using the system method than the traditional method. Second, the correct book is found faster by the system method than the traditional one in most book positions. Third, the usability of the system evaluated by the system usability scale evaluation sheet shows that the developed system is easy to use.