The present invention provides a method and a system for evaluating SOH of an energy storage battery. According to the method and the system for evaluating SOH of the energy storage battery, a DOD time series is obtained according to a SOC curve under complex operation conditions by adopting a derivation method; and the SOH of the energy storage battery after the effect of the SOC curve under complex operation conditions are obtained by cyclic solution based on a SOH attenuation characteristic in different DOD intervals and according to the SOH and a cycle number curve of the interval where the DOD series is located. Different from the prior art which predicates the energy storage life cycle based on a qualitative method, the method and the system for evaluating SOH of the energy storage battery propose a DOD series establishment method and a evaluation method of SOH with the effect of the curve under the complex operation conditions and a multi-DOD series, and are beneficial for improving the accuracy of the SOH evaluation of the energy storage battery.