In the field of power grid energy storage, the key to obtain the rational load power distribution scheme of energy storage system is optimization algorithm. If the algorithm selection is not reasonable or the algorithm itself has defects, it will lead to premature solution process, and only the local optimal solution is obtained instead of the global optimal solution. To solve this problem, a dynamic load power distribution method of microgrid distributed energy storage system is proposed. The method firstly collects the operation data of microgrid distributed energy storage system. Then, considering the average load power loss rate and state of charge (SOC) balance coefficient, a multi-objective distribution function of distributed energy storage system is set up. Finally, under the three constraints of SOC, charging and discharging quantity, and charging and discharging current, the optimal solution of multiple objective functions is obtained by using the improved sparrow search algorithm, and the optimal dynamic load power distribution scheme of microgrid distributed energy storage system is obtained. The results show that with the proposed method, the average load power loss is relatively lower, SOC balance coefficient is relatively higher, and multi-objective function value is relatively smaller. It shows that the distribution scheme is more scientific and reasonable, and can ensure the stable operation of the energy storage system and realize the high quality power supply of the system.