The embodiment of the invention discloses an evaluation method and an evaluation device for evaluating the investment benefit of a power distribution network. The method comprises the following stepsof establishing a power distribution network investment benefit overall evaluation index system, and deriving a monomer evaluation index system according to the overall evaluation index system; according to the data of each monomer evaluation index in each power distribution network monomer item in a target area, determining the score of the power distribution network monomer item; according to the data of an overall evaluation index in the target area, determining the score of each overall evaluation index; and ranking all power distribution network monomer items according to the scores of all power distribution network monomer items. According to the invention, the method and the device are designed for the insufficient fund condition during the construction of the power distribution network. According to the score of each overall evaluation index, the score of each power distribution network monomer item or the ranking result of power distribution network monomer items in the targetarea, an optimal combination of power distribution network monomer items is determined. Therefore, the monomer item construction of the power distribution network is further optimized on the basis ofthe time sequence. The contradiction between the power development demand and the limited investment fund can be relieved, and the utility maximization of investment benefits is realized.