Under the promotion of the "Dual Carbon" policy, the distribution network is facing challenges brought about by the massive integration of distributed renewable energy sources. Efficient power flow analysis has become a critical approach to address these challenges. However, existing back/forward power flow calculation methods require significant time to obtain the calculation order and reactance matrix when dealing with large-scale distribution networks, thus affecting the efficiency of power flow calculations. To address this issue, this paper proposes a method that back/forward sweep power flow calculation method integrated leaf nodes recursive pruning. This method utilizes the topological characteristics of the distribution network to implement recursive pruning on leaf nodes, quickly determining the calculation order for large-scale distribution networks with numerous nodes. It can also obtain the corresponding reactance matrix simultaneously, thereby effectively enhancing the efficiency of power flow calculations. Simulation results indicate that the back/forward sweep power flow calculation method integrated leaf nodes recursive pruning performs better in terms of solution efficiency compared to existing layered and search-sorted forward-backward power flow methods, especially in large-scale distribution networks, where the improvement is more pronounced.