In order to address the bidirectional power flow problem encountered in the operation of ship ring distribution networks, this paper proposes a power flow calculation method suitable for complex ship ring distribution network systems. This method adopts a double-layer architecture. The first layer uses breadth first search to perform loop shedding operations on the circular distribution network, and calculates the power flow through forward backward sweep methods to obtain the voltage imbalance at the loop shedding points and PV nodes. The second layer uses the Niu La method to process the loop point and PV node, and through active and reactive power compensation, the voltage imbalance tends to zero to simulate the characteristics of a multi-source and multi loop distribution network. In order to improve the speed of this method, this paper introduces the sparrow search algorithm to increase the algorithm’s running speed and reduce its convergence iteration times. Finally, the effectiveness of this method was verified through software instance calculations.