Abstract: In order to improve the endurance of electric vehicles, the driving performance optimization and structure design of secondary reducer of an electric vehicle are carried out. Firstly, according to the driving performance requirements of electric vehicle, the overall speed ratio, gear parameters and intermediate shaft parameters of the reducer are preliminarily designed. The vehicle power system is simulated and analyzed by AVL CRUISE software, and the optimal transmission ratio is selected to optimize the transmission performance of the reducer. According to the simulation results of automobile power system, the specific layout scheme of reducer is designed, and the static and dynamic performance of the reducer gear are simulated and analyzed by the finite element analysis software ABAQUS to obtain the bending deformation and force law of the gear root during the working process of the reducer. Finally, the transmission scheme of the reducer meeting the performance requirements is designed.