Abstract: Multi-port power electronic transformer（PET） is the key equipment for the flexible interconnected distribution network.Its decoupling control of ports and coordinated control between regions are the main technologies to ensure the safe and stable operation of the cross-regional interconnection system. This paper uses the isolated modular multilevel converter（I-M2 C） based multi-port PET as the key equipment to propose a structure of flexible distribution network interconnected by medium-voltage DC（MVDC） feeders. First, the technical characteristics of the scheme for the cross-regional interconnected distribution network based on the MVDC feeders are analyzed. A mathematical model of ports in I-M2 C based PET based on the dual-modulation freedom is established. Then, according to the mathematical model of ports and the requirements of different steady-state operation modes, a decoupling control method based on the dual-modulation freedom for each port is proposed. At the same time, the master-slave control strategy between regions in the cross-regional interconnection mode is introduced. Operation modes of the flexible distribution network under various working conditions are summarized. Finally, a 10 k V simulation model is built in MATLAB/Simulink,which verifies the effectiveness and feasibility of the coordinated control strategy for the MVDC interconnected flexible distribution network.