The invention discloses an optimization method for optimizing the differentiated development and investment of an incremental distribution network in accordance with the new electricity reform policy.The method comprises the steps of S1, calculating the annual cost C change of a substation; S2, calculating the annual cost C curve of a line; S3, calculating the annual comprehensive fee Ct; S4, calculating the annual power transmission and distribution amount Rt; S5, constructing a decision-making objective function for realizing the minimization of the annual comprehensive cost; S6, constructing a target function for realizing the maximum net present value of the full-life cycle of equipment; S7, if the level of power transmission and distribution cost is given, obtaining an output resultthrough solving directly according to the steps S5 and S6; if the power transmission and distribution cost is not known, conducting the next step along with the change condition of the planning scale;S8, constructing a calculation formula of the power transmission and distribution cost; S9, setting the initial value J0 of the power transmission and distribution cost; S10, obtaining an annual comprehensive cost; S11, calculating a real-time power transmission and distribution cost Ji; S12, conducting the judgment. According to the invention, based on two differentiated target functions, namelythe comprehensive cost minimization and the full-life benefit maximization, an investment decision-making optimization algorithm adaptive to the differentiated development target of the incremental distribution network is established. Therefore, the planning scheme and the investment scale of the power distribution network are guided and optimized.