The invention discloses a method for establishing a distributed photovoltaic power stealing cost benefit evaluation model based on a B/C (Benefit/Cost) method. The distributed photovoltaic power stealing cost benefit evaluation model based on a B/C method comprises: determining the installed capacity of a distributed photovoltaic power station according to the construction situation of the distributed photovoltaic power station; combined with the installed capacity, the environmental conditions and the generating capacity in former years, estimating the annual generating capacity of the distributed photovoltaic power station; analyzing the equipment composition and the operational mode of different photovoltaic power stealing methods; calculating the cost composition of photovoltaic power stealing under different power stealing operation modes, and establishing a life cycle total cost model under different photovoltaic power stealing operation modes; calculating the power sealing total income of photovoltaic power generation under different power stealing operation modes; and at last establishing a benefit ratio model under different power stealing operation modes. Through the models established through the above method, the profit situation can be calculated under different power sealing modes and different power sealing operation modes, and the power sealing mode which appears with higher possibility can be speculated so as to provide a basis for development and operation of power sealing identification technology for the power sealing mode.