A circulating charging/discharging device for an electric vehicle has a battery assembly, a switch, a controller, a power generator motor, a power generator and a wheel motor. The battery assembly has a charging module and a discharging module connected in parallel. The battery assembly has output terminals connected to the switch. The controller turns on/off the switch and controls operations of the electric vehicle. The power generator motor and the wheel motor connect to the battery assembly through the switch for receiving power from the battery assembly. The wheel motor drives the wheel of the vehicle to let the vehicle move. When the vehicle is started, the battery assembly transmits power to the power generator motor through the switch so that the power generator motor drives the power generator for generating power used for charging the battery assembly. Therefore, the battery assembly is charged when the vehicle is moving.