Abstract: The work about the driving range of an AHEV (auxiliary hybrid electric) is studied in this paper. First, the system structure and working principle of the SHEV is expounded, and then a simulation study is made about the components working efficiency, driving range and fuel economy of the original electric vehicle (EV) and the AHEV under two different control strategy using ADVISOR2002. Based on the simulation results, the series on/off control strategy is determined. Under the control strategy, the driving range of the AHEV is equivalent to that of the EV even when battery numbers are halved. Finally, road experiments are designed and performed.