There is a lack of method support for the transition of substation voltage level in the planning period in the circumstance where the Distributed Generation (DG) permeability continues to increase in rural areas. Thus a dynamic boost planning model and method for substations in low-load areas of an active distribution network are proposed. First, we take the situation of 35 kV substation decommissioning and voltage boost ahead of schedule. A measurement method is proposed to take the equivalent annual value of the whole life cycle cost conversion of the of 35 kV substation to be boosted in the existing site and the scene of the voltage boost. Secondly, aiming at the optimal overall life-cycle cost in the planning period, a mathematical model of rural substation booster planning with DG permeability is established. Thirdly, considering the variation of the power supply area after the substation is built or boosted, a dynamic boost planning method for rural substations of an active distribution network is proposed, and the time sequence of new substations and boost is obtained, based on a weighted Voronoi graph algorithm and a genetic algorithm. Finally, an example is given to verify the effectiveness and practicability of the method. This work is supported by the National Natural Science Foundation of China (No. 51807116).