As electric vehicles become more popular, their impact on the power grid is also increasing. In order to enhance the cooperation between electric vehicles and power grids and make full use of the high flexibility of electric vehicles in grid energy dispatching, this paper proposes a real-time dispatching strategy for electric vehicles based on V2G technology. To reduce the cost of charging and power loss, an electric vehicle scheduling model is established. Then, the grid node performance is analyzed by constructing the network loss sensitivity index, and the time-of-use electricity price is determined based on the grid load. Finally, the power flow calculation and convex optimization algorithm are used to solve the electric vehicle charging and discharging optimal strategy in real time. The proposed strategy is verified by IEEE 33-node distribution system, and the influence of electric vehicle penetration and V2G ratio on the cooperation between electric vehicle and grid is analyzed. This work is supported by National Natural Science Foundation of China (No. 61673174).