The applications, principles and problems of the indoor positioning technology are described in this paper and the typical indoor positioning systems are introduced. By comparing the advantages and disadvantages of the different technologies and the analysis of development tendency, the following conclusions are presented. At the present stage, a successful indoor positioning solution should consider the requirement of customers, environmental characteristics, performance of various positioning technologies, and multiple technologies to improve the performance. The future development of indoor positioning technology will aim toward the decimeter-accuracy seamless outdoor and indoor positioning in wide area.