Abstract: The finite element analysis method is used to study the change of dielectric laser high mirror component surface profile and the distribution of film stress before and after the coating.The simulation results show that the residual stress and thermal stress are distributed in layers, the stress in substrate changes from tensile stress to compressive stress from the bottom to the film surface, and the stress-induced surface changes are in a circular distribution.When the ratio of thickness to diameter is less than 1:20,the deformation caused by gravity cannot be ignored for fused silica substrate.When the surface of fused silica(φ=200 mm, d=2 mm) is a curved surface caused by gravity and the film system is composed of TiO₂-SiO₂ of G│(HL)¹⁰H│A,the change of surface shape of the film-coated component is reduced by 1.45 μm, which corrects the deficiency of ideal plane film simulation and provides guidance for the preparation of large diameter micro deformation coated components.