Aiming at a new type of single cantilever main support structure of space camera, both wave aberration sensitivity model and integrated simulation analysis are proposed to calculate the camera's wave aberration in the lightweight design of optomechanical structure, so as to ensure the imaging quality under mechanical conditions. The proposed wave aberration sensitivity method can model based on the linear relationship between wave aberration and misalignment, which is of great significance to guide the optimal design of optomechanical structure under the constraint of the camera imaging quality. Firstly, the sensitivity model of optical element misalignment and wavefront aberration is derived based on the principle of optical system misalignment. Then, the nodal displacements under mechanical condition are obtained by finite element method, and the misalignment of primary and secondary mirrors is calculated based on best-fit fitting method. The wavefront aberration of the camera is obtained by the optical analysis of the misaligned system. Finally, the two methods proposed in this paper are used for modeling and analysis of a 5 kg level space optical camera, and the corresponding gravity condition analysis and test are also performed. The error of sensitivity model is 16.8% compared with the optomechanical integrated simulation method, and the sensitivity model can be applied to the rapid calculation of system imaging performance in the design phase.