The mirrors play a key role in the space optical system, and it has been developed to the fourth generation of C/SiC composites. C/SiCcomposites have become very important materials for light-weight mirrors because of the advantage of low density, high stiffness and strength, considerable flexibility in structural design and so on.In this paper, the characteristics of four generation of mirror were contrast, the preparation process and the structure design of C/SiC composites were summarized, the development of the C/SiC mirror at home and abroad is reviewed.