According to the shortcomings of present twoway charging and discharging system such as large volume, poor flexibility and low power and so on, this paper proposes a system composed of bidirectional DC/DC converter controlled by space vector and bidirectional DC/DC converter with PWM control and with twoway PWM rectifier, 220V/380V power supply, grid connector and motor drive voltage output. This program has the advantage of being able to switch between 220V/380V to enhance the flexibility and power consumption of electric vehicles, the power devices, which are used in electric vehicle system, being the original devices of eauto, saving cost and vehicle space, and can be used as a mobile power supply to power grid for feedback energy when the electric car is idle. The feasibility of the system is verified by simulation experiments and by analyzing the simulation results so that the twoway vehicle charging and discharging function based on V2G technology can be realized.