This paper introduces the background and basic theory of flexible repeater technology, then analyses the basic working process and principle of flexible repeater on Wideband Gapfiller Satellite (WGS), and summarizes the key technologies during implementation. Meantime, for solving the large capacity and multi-beam connection problems in mobile satellite communication system, the flexible repeater provides the necessary basis theoretical and technical support. Finally, by comparing the tradition repeaters with flexible repeater, this paper points out the flexible repeater possesses the virtue of high power efficiency and high flexibility, and could realize flexible switching of the satellite signals and resources.