Abstract: To meet the requirements of high location accuracy and surface figure accuracy for space mirror set, reducing support weight extremely at the same time becomes the new important research subject in most countries. A topological optimization design for a space mirror support lightweight was presented in this paper. By using finite element analysis technique, the static stiffness of the mirror was analyzed. The analysis results show that the surface accuracy reaches /10 PV, /50 RMS (=632.8 nm) under gravity load, PV value is 13.3 nm, RMS values is 2.9 nm, the mirror component first-order natural frequency is 239 Hz, which is better than traditional structure forms of mirrors, and can meet the application requirements.