Abstract: A large aperture reflector is an important optical element in the inetrial confinement fusion driver with high-power solid laser and the quality of its surface has direct impact on the output characteristics of the whole equipment. In order to study the surface deformation of a large aperture reflector, after comprehensive investigation of the stress-controlling technique of large aperture reflectors, the research was carried out both theoretically and experimentally. Firstly, the model for a large aperture reflector was constructed by means of ANSYS. Then the DPV-S curve,indicating the relationship between deformation and change of pressed area under the effect of gravity, was obtained. Secondly, an interferometer was used to measure the upside and backside deformation of the large aperture reflector. The test result was consistent with that in theory and their difference was only 0.002μm～0.122μm. The results show that the study provides a good method for surface detection, surface control and alignment for large aperture reflectors.