Aiming to solve the problems of low energy utilization and insufficient cruising range of pure electric tractor, a power supply system of pure electric tractor based on super capacitor and battery composite was proposed. By analyzing the working condition characteristics and power demand of pure electric tractor, the topological structure selection and parameter matching of power supply system were carried out. According to the topology of the composite power system and the operating principle of the battery pack, super capacitor pack and DC/DC, a suitable modeling method was selected to model the battery pack, super capacitor pack and DC/DC by using Simulink, taking the lowest energy consumption of power supply as the optimization objective, the energy control strategy of power supply system of pure electric tractor was optimized by using dynamic programming, and the results of dynamic programming were obtained, and the characteristics of working conditions were analyzed, the energy control strategy of power supply based on rules was summarized, the control strategy was simulated by using Matlab/Simulink model. The results showed that the energy consumption of the control strategy based on dynamic programming was 18% lower than that of the rulebased control strategy, which proved the effectiveness and reliability of the energy control strategy based on dynamic programming in energy saving and consumption reduction.