Abstract: As an important demand response resource, electric vehicles (EVs) play an important role in the smart grid. Two kinds of electric vehicle aggregator (EVA) dispatching strategies based on price and incentive demand response, fixed contract strategy and flexible contract strategy, are proposed. The fixed contract strategy assumes that some EV users sign a fixed incentive agreement with EVA. The flexible contract strategy takes the EV charging process as the dispatching cycle, considering the selection of EV users in each dispatching cycle. The revenues and load fluctuation of EVA are optimized in two strategies. Then, the effects of the numbers of EVs participating in incentive dispatching and different incentive discounts on the comprehensive benefits of EVA and EVs are analyzed. Finally, the improved multi-objective particle swarm optimization algorithm is used to solve the problem. The simulation results show that the fixed contract and flexible contract strategies can improve the efficiency of EVA, while the flexible contract strategy can reduce the cost of EV users.