Abstract:This paper mainly studied the method and process of electric driving system modification for subcompact. Based on the structure parameter of Alto subcompact, the authors did the match design of electric driving system modification. According to the requirements of acceleration time, driving range and hill-climbing ability, the key parameters and structure of the driving motor, storage battery and driving system were determined by the vehicle dynamics calculation. By using the Advisor software, the dynamic model of the Alto subcompact was set up. Based on this model, the performance of Alto subcompact after pure electrical modification was numerically investigated. The simulation results showed the method and process of match design are correct and feasible. Because of the complexity of experimental environment in test,the performance test results of real vehicle after pure electrical modification have a little difference, but the match design and modification have almost reached the primary targets.