Relay communication satellites play a very important role on the lunar far side and pole areas exploration missions. Queqiao relay communication satellite was developed to provide relay communication support for the lander and the rover of Chang’e-4 mission landing on the far side of the Moon. From entering into the halo mission orbit around Earth-Moon libration point 2 on June 14, 2018, it has operated on the orbit more than thirty months. It worked very well and provided reliable, continuous relay communication support for the lander and the rover to accomplish the goals of Chang’e-4 lunar far side soft landing and patrol exploration mission. Exploration of the lunar south polar regions is of high scientific interest. A new relay communication satellite for Chinese south pole exploration mission is also under study. The system design and on-orbit operation status of Queqiao relay communication satellite were summarized in this paper. The system concept of the relay communication satellite for lunar south pole exploration missions is proposed. Finally, the future development and prospect of the lunar relay communication satellite system are given.