Airborne directed energy device has the functions of optical imaging a nd high power laser emission.In order to ensure the effective operation of airb orne directed energy device with high energy laser,the co-aperture optical sys t em should be able to output laser with high beam quality in a large temperature range while keeping the size of the optical and mechanical system small.This po ses a high challenge to the optical and mechanical design of the co-aperture sy s tem.In this paper,the initial structure design model of co-aperture optical s y stem for airborne spherical pod is established to meet the requirements of minia turization imaging and high beam quality output.An optical and mechanical syste m optimization design method is proposed to ensure the effective operation of th e system in a large temperature range.Combined with an example,the design of a co-aperture optical and mechanical system with a range of 1km~10km and Φ 500mm envelope is completed.The results of the optical me chanical integrated calcul ation and analysis are obtained by using the physical optical analysis module an d the finite element analysis.The good adaptability of the system in large temp erature range is verified,which meets the engineering application requirements of high-power laser system.