In order to quickly obtain the effect of different bonding processes on mirror surface shape, the process of adhesive curing and shrinking was simulated. Firstly, according to the free curing model of colloid, the functional relationship between mirror deformation and adhesive shrinkage was derived. Then, based on the temperature loading method, the finite element model of adhesive curing shrinkage was established, and the influence of adhesive quantity, adhesive position, distribution mode and colloidal parameters on the surface shape of large aperture rectangular mirror was analyzed, and the optimization scheme of high surface shape precision bonding was obtained. In the process of rectangular mirror assembly design, the influence of whether there is a frame on the mirror surface shape simulation results was compared. The mirror surface shape was taken as the response constraint, and topology optimization of the frame was carried out to obtain a lightweight configuration for post-processing, including smooth and smooth processing, structural reconstruction processing and optimal configuration of frame materials. The weight of the frame was 7.93 kg. Compared with direct structural reconstruction, the optimized configuration of frame materials reduced the weight by 62.12%. The results show that the PV value of the mirror surface is 53.26 nm, the RMS value is 10.98 nm, and the maximum stress value is 0.04 Mpa when the side 6-point flexible bond ring is used, the non-uniform near-homogeneous surface distribution, the colloid diameter is 10 mm, and the colloid thickness is 0.1 mm. Finally, the environmental adaptability of the mirror assembly is analyzed, which satisfies the Rayleigh criterion of the optical system and the mechanical conditions of the structural design. The research results can provide reference for the optimization scheme of high surface shape precision bonding of large aperture rectangular mirror and the optimal design of support structure. © 2023 IEEE.