This paper proposes an automatic calculation method for the redundancy optimization scheme of communication satellite load, which comprehensively uses the shortest path query and Kruskal minimum spanning tree algorithm, aim at solve the problems of low computing efficiency of the back scheme in the M:N large number redundancy ring structure, and iterative switching scheme cannot be provided when multiple devices fail at the same time. This method is based on the premise that the cable connection relationship of the satellite device is fixed. Through the shortest path query method and the minimum spanning tree algorithm, Could give the main and multi-level backup scheme of the equipment serving for the channel is given in the form of the backup matrix. In this method, the calculation process of matrix establishment and optimization which will have a large calculation scale will be executed as preparation work, and does not need to be repeated; For specific switching requirements, only direct/iterative switching scheme search is required according to the matrix. It improves the efficiency of real-time scheme calculation in the process of satellite long-term on-orbit management; And be able to provide a recursive backup scheme to improve the robustness of the system.