The relay communication is a key problem for lunar exploration missions，especially for the landing and cruising on the lunar far side and polar areas，and for the manned lunar exploration missions. The research and development status about lunar relay communication satellite system throughout the world are analyzed. Based on the analysis on the requirements for lunar relay communication missions，the implementation approach is analyzed for relay communication system scheme，orbit selections，etc. The characters of relay communication system are analyzed to support generating the development strategy. Finally， the satellite design scheme is illustrated.