the search of power system controlled islanding surfaces problem is transformed into a single-objective multi-constraint optimization problem, and a new searching method for power system controlled islanding surfaces considering coherent generators is proposed. The magnitude of the reactance between nodes reflects the electrical contact degree of the two nodes, and the reactance value between the nodes is used as the line weight. The Dijkstra algorithm is used to calculate the minimum reactance value between the generator in the coherent generators group and get the coherent generators connection diagram. The prim algorithm is used to get the minimum spanning tree of the coherent generators connection diagram, The minimum spanning tree is equaled as a node, thus ensuring the connectivity of the generators in the island. The Dinic algorithm is used to obtain the minimum power flow cutset between non-coherent generators groups, and the optimal solution of power system controlled islanding surfaces is obtained. The simulation of the IEEE-39 node system verify that this method can determine the position of islanding surfaces quickly and accurately.