In order to solve the problems of many devices, large space and high investment in the existing topology of flexible interconnection devices (FID), a topology of series flexible interconnection devices based on multiplexing bridge arm dual active bridge (DAB) is proposed in this paper. Utilizing the traditional DAB, this paper analyzes the principle of the circuit working in DC/AC state with subside bridge arm multiplexed, and the instantaneous power transmitted bidirectional in the topology is calculated theoretically. Based on the traditional series type FID, the circuit is applied to the flexible interconnection of medium-voltage distribution network, and the power-current double-loop control strategy is designed to realize the energy exchange between multiple AC systems and converter stations. Finally, the simulation results illustrate that the two 10 kV AC systems can transmit energy through this topology when the phase angle differs.