With more and more electric vehicles (EVs) integrated into power grids, the charging of EVs may impose great challenges on dispatching and operating of both transmission and distribution grids. A literature review on the impact of EVs charging on both transmission and distribution grids as well as optimal dispatch study is presented in this paper, which includes distributed smart charging, EVs and microgrids coordination, EVs and large-scale wind energy coordination, and so on. It is concluded that if the issue of EVs charging and even discharging behaviors can be effectively dealed with through smart distribution dispatching algorithm, the challenge of EVs charging may create a new opportunity for power grids to solve the problelm of peak load shifting and improve the utilization of new energies shch as wind energy and solar energy.