The invention relates to a computing method for distributed power maximum access capacity in a flexible power distribution network based on SNOP. The computing method comprises the following steps: establishing a DG extremity access capacity model, using a network tide, feeder capacity and node voltage, distributed power single-point maximum access capacity and SNOP power as constraint conditions, selecting DG access capacity in maximum FDN as an optimal object, and adopting various population genetic algorithms to solve the model. According to the computing method, the distributed power maximum access capacity at an appointed position can be computed, and the optimal distributed power access position and capacity combination in the whole network can also be obtained in a planning angle.