Abstract: To achieve tracking and identification of long-distance aerial targets while meeting the practical requirements of airborne platforms for limited space and weight of optical imaging systems, this paper designs a long-focal-length(850 mm)/wide-band(400 nm～1 100 nm) Cassegrain TV camera (hereinafter referred to as the TV camera). The Cassegrain optical system is a reflective design, which has no chromatic aberration and can achieve a long focal length within a relatively short physical size, making the entire camera system more compact.. Therefore, the design and simulation of the Cassegrain optical system based on the optical design software CODE V and the 3D modeling software UG are carried out; the modal, gravity load, thermal load, impact/vibration and other simulation analyses based on the ANSYS finite element simulation software are conducted, and the primary mirror and main structural parts are optimized for lightweight design multiple times according to the simulation results. The theoretical research on the adhesive layer thickness of the large-aperture primary mirror and the minimum bonding area of the secondary mirror's adhesive layer is carried out, which is used to guide the bonding of the primary/secondary mirrors and the opto-mechanical assembly and adjustment of the TV camera. The simulation and test results show that: the modulation transfer function (MTF) of the optical system is greater than 0.5 at 70 lp/mm; the diameter of the spot diagram is less than the pixel size of 6.5 μm; the lightweight design results meet the mechanical strength requirements and the weight is reduced by 16.7%; the laboratory optical resolution is 1.5"; the image quality is good and the image plane is stable at an about distance of 20 km. The design, simulation and test have all achieved the preset goals, accumulating certain engineering practice experience for the optical, mechanical and thermal design and simulation of subsequent complex opto-mechanical systems.