The invention provides a capacity allocation method of an energy storage system to meet the frequency modulation demand of a high-wind-power-permeability system. The capacity allocation method is characterized by comprising a high-wind-power-permeability power system frequency modulation demanding step and an energy storage system capacity calculation step; whether a frequency curve keeps in a safety domain or not is tracked in real time according to the bilateral liquidity of battery energy in order to meet the frequency modulation demand of a high-wind-power-permeability power system, so that the system frequency is prevented from being deviated from a standard range, and safe running of the power system is ensured; moreover, a relationship between energy storage capacity configuration and an energy storage system tracking frequency curve control proportion coefficient K

is provided, so that a basis is laid for frequency modulation of an auxiliary power system for a large-scale energy storage system. The capacity allocation method has the advantages of scientificity, high adaptability, good effect and the like.