The invention provides a micro-grid cell energy storage system frequency modulation control method based on a BP nerve network. The method comprises the steps of: measuring a real-time frequency value of a micro-grid cell energy storage system; obtaining the frequency difference between the real-time frequency value and a rated frequency value of the micro-grid cell energy storage system, inputting the frequency difference into the BP nerve network, and carrying out intelligent inference so as to obtain current optimal parameters of a PI controller; according to the current optimal parameters of the PI controller, carrying out parameter setting on the PI controller, and utilizing the PI controller after parameter setting to obtain an inverter-controlled active power difference reference value of the micro-grid cell energy storage system according to the frequency difference; and obtaining an active power reference value according to the active power difference reference value, and carrying out system frequency modulation on the micro-grid cell energy storage system by means of PQ inversion controlling. By adopting the method, the precision of active power control of the micro-grid cell energy storage system and the stability of the micro-grid frequency are effectively improved.