Abstract: The relay communication is a key problem for lunar exploration missions,especially the landing and cruising on the lunar farside and polar areas,as well as the manned lunar exploration missions. The research and development status are analized about lunar relay communication satellite system throughout the world. Based on the analysis on the requirements for lunar relay communication missions,the implementation approach are analyzed for relay communication system scheme,orbit selections,etc. The technical development trends for future lunar relay communication satellite system are also given in this paper.