Grid-connected electric vehicles are not only the random loads but also the mobile storage components and their charge and discharge behaviors have big effects on the grid operation. Moreover, modeling of electric vehicles is the foundation for studying grid integration. Electric vehicles’ charge and discharge model which consists of a voltage-source rectifier PWM and bi-directional DC-DC converter is established. A novel charge control strategy for electric vechicles is introduced which uses current loop control in the current constant stage and switches automatically to voltage and current double closed loop controls when the system reaches to the set voltage values to achieve constant current and constant voltage charge. Finally, the control strategy is simulated by using MATALB/SIMULINK and compared with the charge strategy by adopting voltage and current closed loop controls merely, which demonstrates the effectiveness of charge and discharge strategy and proves the superiority of the proposed automatic-switchover charge control strategy.