Abstract: With the large-scale access of electric vehicles in the distribution network, the trend of charging load growth caused by their disorderly charging behavior is becoming more and more significant, which leads to many problems such as overloading of distribution transformers, increasing network loss of distribution transformer areas, and load imbalance. In this paper, we focus on the improvement of EV acceptance capacity in distribution transformer areas, and propose a cooperative optimization method for EV charging facilities in multi-distribution transformer areas based on flexible interconnection, taking into account the willingness of users to participate, the charging cost, user satisfaction, and the security of the distribution network, combining with the power of SOP and the ability of mutual transmission, and realizing the optimization of EV charging facilities in multiple distribution transformer areas, taking into account the willingness of users to participate, the charging cost, user satisfaction, and the security of the distribution network. The interconnection and mutual supply between areas is realized by considering the willingness of users to participate in charging, user satisfaction, security of distribution network, etc., and combining with the power of SOP. Example analysis proves that this paper's method can reduce the risk of transformer overload, greatly increase the economics of area operation, and achieve charging load transferring and flexible resource sharing through flexible interconnection equipment between areas, thus greatly improving the acceptance capacity of EVs in distribution transformer areas.