As the current capacity of the existing electrochemical energy storage system is too low to meet the problem of power supply enterprises’ power equipment operation demand. Therefore, this paper introduces the demand-side response improvement particle swarm algorithm to carry out the research on the capacity optimization of electrochemical energy storage system. According to the operation characteristics of the energy storage system, the charging and discharging model of the electrochemical energy storage system is established; the demand-side response improvement particle swarm algorithm is used to set the capacity optimization objective function of the energy storage system; and the capacity configuration plan of the electrochemical energy storage system is finally completed. By examining the performance of chemical energy storage systems before and after the application of optimization technologies, it’s finished that the capability of the system has been considerably improved when optimization, which might give additional power conditions for additional power instrumentation and promote the development and development of power offer enterprises.