Abstract: To solve the problem of the dispatching and the users' settlement for the participation of EV aggregators in frequency regulation services, this paper proposes a three-part operation framework that combines the day-ahead energy/reserve optimization, the real-time dispatching, and the revenue sharing between aggregators and EV owners. By defining the operating margin restricted by the charging demand, the complexity of the dual charging/regulation variables is reduced, and the charging energy and reserve capacity can be jointly optimized day-ahead. In the processes of the real-time power dispatching and the frequency regulation settlement for each user, the charging power and regulation power can be decoupled to achieve a quick solution and a fair distribution, and the user's charging demand can be ensured. Simulation results validates the proposed framework, and to encourage the participation of theEV owners, two contract mechanisms with different levels of participation are designed to demonstrate and compare the charging and revenue under the two contracts from the user's point of view.