The invention provides an SOC operation scope determining method and device of an energy storage battery module. The method comprises that N groups of SOC scopes are preset, simulated operation test of the N groups of SOC scopes in a wind and light power smooth mode is carried out, a maximal extreme voltage difference of N batteries and a maximal voltage standard deviation coefficient of N batteries are obtained, the maximal extreme voltage difference and the maximal voltage standard deviation coefficient of the N batteries are compared with preset battery voltage extreme different limit and voltage standard deviation coefficient limit respectively to obtain first and second comparison results respectively, according to the first and second comparison results, M groups of SOC scopes withina normal operation range are determined, and an SOC operation scope of the energy storage battery module in the wind and light power smooth mode is determined. The method and device has significancein determining the SOC operation scope of the energy storage battery module in the wind and light power smooth mode, making available charge and discharge capacity of an energy storage power station clear, and realizing smooth and acute control of the wind and light power.