Demand response(DR)has obtained more methods with a growing number of distributed energy storage systems(ESSs)tied to the grid on the demand side.Responsible capacity of ESSs is one significant aspect of DR ability of the demand side.The article proposes a method to identify the responsible capacity of ESSs in the distribution grid to estimate demand side ESSs’responsible capacity under different circumstances.The work considers various DR co-control aims of different kinds of loads and solves the operation strategy of ESS and changeable loads by particle swarm optimization, then calculates the responsible capacity of ESSs.The results show that load structure and distributed power outputs have an impact on the responsible capacity, to achieve the balance between security and reliability of power system operation and efficiency of ESSs, proper capacity allocation should take control objective into account.