In this paper, a supercapacitor control system is designed to improve the motion performance of small unmanned vehicles. The supercapacitor is used as the auxiliary power supply for the chassis of the unmanned vehicle. When working at low power, the lithium battery supplies power to the chassis and charges the supercapacitor. When climbing or accelerating, the supercapacitor is used to assist the power supply to improve the body’s movement ability. The current and voltage values are collected by high-precision sensors and the system charging control is completed by fuzzy PID. It has a good effect on the test, which significantly improves the motion performance of the unmanned vehicle.