The invention relates to a method for planning substations of a power distribution network. The method comprises the following steps that each 110-kV substation is arranged according to the N-1 principle distribution pattern, the capacity-load ratio ranges from 1.8 to 2.1, each 35-kV substation is arranged according to the N-1 principle distribution pattern, the capacity-load ratio ranges from 1.6 to 1.8, the distribution transform capacity-load ratio of each 10-kV substation ranges from 1.5 to 2.0; a boost and expansion project, the number of newly established substations and the main varying capacity are determined according to the target capacity-load ratio of each substation and the current operation and distribution situation of the substations of the power distribution network, and then the station location of each substation and the power supply radius are determined; the minimal investment and the minimal annual operation cost serve as objective functions, the constraint condition refers to the fact that the load requirement is satisfied, and an optimized operation is conducted through the objective functions; the minimal investment and the minimal annual operation cost of substation planning are determined; the number of the substations needing to be newly established and the number of the substations needing capacity increase are obtained through calculation and therefore the problems that the load rate of an existing circuit is ultra-high, the capacity-load ratio of each substation is ultra-low, and operation and dispatching are not flexible can be solved through the minimal investment and the minimal annual operation cost.