Abstract: In the context of the increasing demand for frequency regulation in the new power system and considering the low actual utilization rate of user-side energy storage, a sharing mode of microgrid-owned distributed energy storage in the grid-connected state is proposed. This model enables internal energy storage sharing to meet the basic peak regulation needs of multi-microgrid systems, while external sharing of the secondary frequency regulation of auxiliary power grids is utilized to obtain additional benefits. Taking the multi-microgrid system with shared energy storage as the research object, a peak regulation instruction allocation strategy is proposed during internal sharing that comprehensively considers the balance of energy storage SOC and life loss. In this manner, peak regulation can be realized while reserving frequency modulation margin for energy storage systems and reducing energy storage regulation loss. When sharing with the outside world, a rolling calculation method for frequency modulation capacity declaration and a frequency modulation instruction allocation strategy that comprehensively consider both the current peak regulation plan and future peak regulation demands of energy storage are proposed, ensuring that energy storage supports power grid frequency regulation on the basis of leaving a margin for the subsequent peak regulation. Based on the data from a multi-microgrid system in a certain region, simulations and comparisons are carried out, and the effectiveness of the proposed strategy is verified through a case study.