The embodiment of the invention provides an optical storage micro grid system for realizing energy storage capacity dynamic optimization. According to the power output data of photovoltaic power predication and the requirement data of load power predication, a set algorithm is employed by an energy storage capacity dynamic optimization module to calculate the proportional value between emergency power backup capacity and smooth fluctuation capacity, and the proportional value is transmitted to an energy storage battery management system through a DSP control module. The energy storage battery management system adjusts the emergency power reserve capacity and smooth fluctuation capacity in an energy storage battery, and thus the proportion between emergency power backup capacity and the smooth fluctuation capacity is in accordance with the proportional value after the adjustment. According to the embodiment of the invention, the energy storage capacity of the optical storage micro grid system can be dynamically optimized, the energy storage utilization rate of the optical storage micro grid system can be raised, under the premise of ensuring emergency power supply, the power fluctuation of a grid-connected point is inhibited to the maximum, and the utilization of renewable energy, energy saving and loss reduction are facilitated.