In order to work smoothly and move quickly on a narrow vehicle-mounted platform, the vehicle-mounted radar needs structural design and lightweight design. In this paper, a set of segmented antenna radar driven by driving motor and hydraulic mechanism is designed, which realizes rapid expansion and contraction. At the same time, based on the statics analysis module and topology optimization module in ANSYS software, the original model is mechanically checked and lightweight designed under specified working conditions, and the antenna surface skeleton model is reconstructed, and a new lightweight model is obtained. Finally, the weight isreduced by 16.065%, which greatly improves the maneuverability, reliability and portability of the vehicle-borne radar.