Abstract: As a mobile energy storage unit in power grid,EV not only "obtain" energy from the power grid,but also provide such V2G（Vehicle to Grid） service as emergency power and frequency controlling,which make the power grid operate more safely and economically.The modeling of EV Vehicle to Grid is the basis for various calculating and analyzing.In this paper,the concept of equivalent smart charger is proposed based on the logic control,and the control strategies with agent-based EV involving in frequency control are analyzed by referencing to the methods used in controlling other power system energy storage components.Furthermore,the model of EV involving in frequency control is built using user-defined modeling methods in PSASP.In the end,the simulation and calculation are carried out with the 3-machine 7-bus system（EPRI-7） by using of proposed model.The results show that the model can well reflect the frequency response characteristics of EV system,and frequency-control power can be regulated according to frequency deviation,then the system frequency can be recovered to rated value.The proposed model can be used to analyze and calculate complex power grid.