Abstract: In view of the frequent battery feeding of the police hydraulic automatic roadblock vehicle, this paper analyzed the principle of power supply and vehicle operating conditions, and drew the conclusion that there were two failure reasons: no backup starting circuit and no shunt system for high power equipment. Through the design of main and auxiliary power supply system, the problem of chassis battery feeding was solved, and the real-time start-up of the vehicle was guaranteed. At the same time, by the using of the isolator effectively blocked the charging between the main and the auxiliary batteries pro-tected the safety of the vehicle. The shunt system design of the power collector was carried out by using the power port of the chassis gearbox. This way of using mechanical energy instead of electrical energy ensured the power demand of the high-power equipment and relieved the pressure of the vehicle battery. At the same time, the feasibility of the scheme was verified by the real vehicle test, which provided a design idea for the subsequent power supply design of the modified vehicle.