The impact of electric vehicles to power grid whencharging is analyzed, the main research is about the influence to the balance of power grid load. Then, the electric vehicle chargingload is modeled, and time probability distribution of users’trip isanalyzed, The demand for electric vehicle charging load is calculated by Monte Carlo simulation method, in order to study throughout the time distribution of 3 000 electric vehicles’charging demand,The optimization model of regional power supply system including photovoltaic power generation system is established. Meanwhile,dynamic electricity price is used as incentive to guide electric vehi-cles to carry out orderly charging, so as to participate in power gridancillary services. With the minimum power fluctuation product and the lowest charging cost, the weighted function is taken as the objective function, combined with the four constraints, the geneticalgorithm is used to solve the model, and the optimal chargingscheme is obtained. Finally, an example is given to verify that the model can realize the function of shifting load, cutting peak and filling valley.