Electric vehicles can be used as standby power on the demand side through V2G technology. In this paper, a multi-objective optimization model is established, cost of economic dispatch and charging cost of EV owners are taken as the model's objectives, and the electric vehicles are used as standby power through coordinated charging in the process of economic dispatch. After meeting all the constraints, the model is simulated by NSGA-II algorithm. Besides, the electric vehicles' load charactristics, the real load fluctuation, the real wind output and the fault outage of generators are simulated hourly by using Monte Carlo algorithm.Experimental results show that this model can save the cost of economic dispatch and the charging cost of EV owners by choosing the right result among the pareto. It can also narrow the gap between peak load and valley load.