The decoupling ring of the electromagnetic loop of the power system has two sides. For the sending end system, the loop-opening operation can reduce the short-circuit current to a certain extent, but at the same time, the stability margin of the system may be reduced.Therefore, it is worthwhile to study the necessity, timing and method of unwinding the electromagnetic ring network at the sending end. It is necessary to carry out research to establish an evaluation index system for the decoupling loop of the electromagnetic ring network at the sending end, and to study the timing and method of unwinding the electromagnetic ring network.In order to judge whether to solve the ring, indicators need to be analyzed, and there are certain contradictions between the indicators. Game theory can effectively deal with the relationship between the contradictory indicators and obtain the optimal solution.In this paper, aiming at the characteristics of the electromagnetic loop network of the sending end, the index system of the decoupling loop of the electromagnetic loop of the sending end is established, and the cooperative game in the game theory is used to game the index, and the weight of the index is obtained. A method based on cooperative game is proposed to weight the index, and the comprehensive criterion of the decoupling loop of the electromagnetic ring network is obtained. The effectiveness of the proposed method is verified by an example of the electromagnetic ring network of the Chengde delivery channel.