The invention discloses a fault rate calculation method for electric transmission and transformation equipment on the basis of state overhauling, and belongs to the technical field of the state overhauling of the electric transmission and transformation equipment of a power system. On the basis of a total-state integration method, an equivalent state scoring model is introduced in, the fault rate of the equipment is solved by an equivalent state scoring method, and an obtained result of the fault rate is completely the same with the result of the fault rate, which is obtained by the total-state integration method, of the equipment. According to the fault rate calculation method, the fault rates of the equipment under different health processes and states can be accurately calculated, and meanwhile, influence on the fault rate of the equipment by power-off overhauling can be correctly reflected.