The invention relates to an energy storage system benefit factor evaluation method and system, and the method comprises the steps: collecting system parameters of an energy storage system and operation parameters of the energy storage system in the whole life cycle, and sequentially substituting the system parameters and the operation parameters into a pre-constructed evaluation index system according to a preset sequence for calculation; determining a benefit factor of the energy storage system in the whole life cycle according to the calculation result; wherein the evaluation index system comprises first-level evaluation indexes constructed in a layered manner and sub-indexes of the first-level evaluation indexes. The invention provides a full life cycle evaluation system architecture ofthe energy storage system, the operation characteristics of distributed energy storage are considered, the full life cycle process of the distributed energy storage is evaluated in detail, the systemis simple, and the profit estimation coverage level is wide.