In order to solve the problem that that the output fluctuation of renewable energy may affect the stable operation of regional power grid, a real-time control strategy using electric vehicles to smooth regional load fluctuation is proposed. Firstly, the charging energy boundary model is established to determine the charging and discharging margin of EV at each moment, considering the dispatching capability of EV. Secondly, the first-order filter algorithm is used to determine the total dispatching power of aggregated electric vehicles. Finally, the total charging power of aggregated electric vehicles is determined and power distribution is carried out. Finally, the effectiveness of the ordered charge and discharge control strategy proposed in this paper is verified by time series simulation.