Recently, with the rapid growth of electric vehicle (EV) and development of Vehicle-to-Grid (V2G) technology, EVs participating in frequency regulation service to support power grid operation has been seen as one of the most promising power grid ancillary services provided by EVs integrated in grid. The dispatching strategy of EVs determines the feasibility and efficiency of EVs participating in frequency regulation, which have been received extensive researches. This paper will review the current dispatching strategies of EVs participating in frequency regulation. At first, the system structure of EVs participating frequency regulation is introduced. The stability and economy of EVs participating frequency in grid are analyzed. Secondly, the existing dispatching strategies are categorized into strategies for stability problem and strategies for economy problem, which are discussed in detailed. Finally, the existing problems and the future researches in EVs participating in frequency regulation on power grid are summarized.