The invention provides a risk prediction method and device for power system relay protection, and belongs to the technical field of power system relay protection. The risk prediction method for relayprotection of the power system comprises the following steps that simulation testing is conducted on the relay protection process of the power system, and severity indexes and occurrence probabilitiesof all risk consequences in the relay protection process of the power system are obtained; wherein the risk consequence comprises at least two of load shedding, power supply isolation and power gridsplitting; calculating a risk index of each risk consequence according to the occurrence probability and the severity index of each risk consequence in the relay protection process of the power system; and a comprehensive risk index of power system relay protection is calculated according to the risk index of each risk result. According to the technical scheme provided by the invention, the calculation process is relatively simple, and the problems of complex algorithm and low working efficiency when the relay protection risk of the power system is predicted in the prior art can be solved.