Aiming at the contradiction between the speed requirement of power flow calculation under frequent simulation operation instructions and the extremely limited computing resources of the embedded marine power simulation training system, a power flow calculation algorithm for marine power grid based on ordered BDL tree set was proposed. The algorithm optimized the node numbering method on the basis of common methods, and regarded the multistation marine power system in the actual openloop operation mode as the ordered BDL tree composed of multiple radial power grids. Each ordered BDL tree contained the main power distribution board, distribution layer and load layer in a single power station, and integrated the generator flow into the main power distribution board layer, avoiding the problem of node numbering mutation in the common power flow algorithms. The time complexity analysis results and the actual operation results of the algorithm were analyzed and compared, which showed that the proposed algorithm was better than the common marine power flow algorithms.