The invention discloses a large-scale power generator hierarchical out-of-step protection scheme coping with a parallel operation mode of multiple power generators sharing a bus, and belongs to the technical field of electric power system relay protection. The out-of-step situation of parallel machine groups sharing the bus cannot be coped in the prior art. Station domain layer out-of-step elements and in-place layer out-of-step elements are arranged to monitor the state of the power generators in real time, and out-of-step oscillation of the parallel operation generator sets sharing the bus and an out-of-step mode are comprehensively judged so that the performance characteristics of out-of-step protection of all the power generators of the in-place layer are adjusted in real time according to the number of the actual operation power generators sharing the bus and the out-of-step mode, and the generator tripping strategy of out-of-step protection is optimized from the angle of the station domain layer. According to the hierarchical out-of-step protection scheme, an engineering problem that a conventional out-of-step protection scheme cannot effectively cope with operation out-of-step oscillation of multiple generators sharing the bus can be greatly solved, reliability of out-of-step protection action can be effectively enhanced, and the safety requirements of both the power generator sets and a power grid can be considered.