Abstract: With the rapid development of new energy in China,the frequency fluctuation of power grid and other problems are caused.Battery energy storage is widely used to assist traditional units to participate in frequency modulation services. Firstly,this paper combs the existing energy storage related policies and relevant literature in China,and summarizes the evolution law of energy storage assisted frequency modulation market environment. Then in the first part of the article,it focuses on the principle process of traditional unit frequency modulation and battery energy storage system participating in primary frequency modulation,and compares the differences between virtual droop control and virtual inertia control strategy in detail;In the second part,the battery energy storage system participating in secondary frequency modulation is deeply analyzed,and the stage power distribution is analyzed in detail. At the same time,a control strategy model considering multiple constraints is proposed,which provides an effective reference basis for the energy storage power station participating in frequency modulation output. Finally,constructive suggestions are put forward for the future development of energy storage system,and the next research direction is prospected.