In order to solve the problems of long manufacturing cycle and high processing cost of mirrors in reflective optical systems of space cameras, a method for manufacturing metal mirrors based on additive manufacturing process is proposed.This paper designs an open honeycomb structure on the mirror backplane,mirror blank is prepared by additive manufacturing technology.Preliminary improvement of surface quality with rough machining and diamond turning.Then, a high-precision mirror surface is obtained through surface modification and secondary diamond turning.The diameter of the prepared mirror is 110mm, mass reduction rate of 70% and surface shape accuracy is better than ?/15 RMS(? =632.8nm).The results show that the metal mirror prepared by this process can meet the requirements of high-precision reflective optical systems.The research work in this article can provide technical reference for the application of additive manufacturing technology in the field of optics.It has important reference and guiding significance for the research and application of related fields. © 2022 SPIE