Mirror assembly is the important front module for the coarse pointing element of satellite laser communication. The structural and environmental adaption of the mirror assembly has a great influence for the performance of the laser communication system. To solve the design problem of the mirror assembly, the design of SiC mirror assembly and surface simulation for CPA is researched. First, the lightweight structure of SiC mirror is designed. Besides, to reduce the influence for the mirror surface change caused by the mismatching of different linear expansion coefficient, the flexible supporting structure is designed to realize the connection between the mirror and supporting structure. Second, the high-precision algorithm based on discrete error elimination technique for surface parameter of mirror is proposed and the correctness of the algorithm is validated. The validation result demonstrated the precision of proposed algorithm is higher and can satisfy the engineering demands. At last, the surface data of finite element analysis for the SiC mirror is processed by the developed program with high-precision algorithm; the surface parameter of mirror is obtained under the loadcases with gravity and thermal deformation. Based on the calculation result of surface parameter, the structural design of mirror assembly for CPA is verified and the fundamental data is provided to revise the structural design parameter of the mirror. A new technical reference is presented for the supporting structure design of mirror and the simulation technique of optical surface. © 2019 Elsevier GmbH