The Long March 5（LM-5） series launch vehicle is the new generation large launch vehicle of China, which undertakes China’s lunar exploration project, deep space exploration and other national key projects. LM-5 series launch vehicle booster is the largest booster in China. The booster provides 90% takeoff thrust for the LM-5 launch vehicle. In order to ensure the successful development of the booster, the overall scheme and a number of key technologies of the booster are put forward. The engineering and technical problems of these key technologies are overcome in the development process, which lays a solid foundation and accumulates rich experience for the success of the LM-5 launch vehicle and the large cryogenic launch vehicle. Up to now, LM-5 series launch vehicle boosters have successfully completed flight tests, promoting the development and application of follow-up boosters.