To meet the requirements of high dynamic characteristics and overcome the low quality of the main support structure, an optimized design was devised and test verification of the main support structure was conducted. First, to solve the problem that classic support structures could not be applied to this system, a general structural form combining a frame-type structure and a thin-walled tubular structure was proposed. This form conveniently integrates the hood and structure to improve quality and ensure rigidity. Second, multi-variable integration optimization was adopted to improve the first-order mode from 127 to 156 Hz when the quality requirement was also met, thereby effectively improving the dynamic characteristics. Thereafter, to determine the influence of the vibration environment on the system MTF, the influence of the vibration environment on the system MTF was analyzed by combining finite element analysis and a sensitivity matrix. The scope of application demonstrates that the structure could be applied to an airborne system with a pixel size of >10 μm. Finally, the effectiveness and feasibility of the design method and analysis process were verified by a vibration test and a wavefront aberration detection test. The optimized design method proposed in this paper can provide reference for the optimized design of airborne remote sensing instrument structures. This paper will contribute to the development of structure design techniques for airborne remote sensing instruments.