Focusing on the issues of high distributed generation in the distribution network, this paper presents an SOP capacity allocation method for flexible interconnected distribution networks based on sensitivity analysis. Firstly, the improved sensitivity analysis is used to determine the best SOP installation position; Then, the number of SOPs is set in advance, and the location and capacity of SOPs are optimized using the second-order cone programming algorithm, with the minimum annual cost of distribution network as the optimization goal. Finally, this optimization method is verified on the modified IEEE 33-node distribution system model. The results show that the application of the optimization strategy proposed in this paper can significantly reduce the annual operating cost of distribution network and improve voltage stability, and the proposed model can effectively adjust the location and capacity of SOP access, thus improving the economic benefits and reliability of active distribution network.