The invention discloses a nuclear power station equipment reliability grading method and system and a readable storage medium. The method comprises the steps that equipment is graded from the dimensionality of equipment criticality; for key equipment and important equipment in a grading result, the equipment is graded from the dimension of the operation frequency of the equipment, the equipment isgraded from the dimension of the working environment of the equipment, and the equipment is graded from the explicit and implicit dimension after single failure of the equipment; the method has the beneficial effects that the method is suitable for equipment reliability grading identification of the high-temperature gas cooled reactor, equipment grading is carried out from four dimensions of equipment criticality, operation frequency, working environment and explicit implicit, and equipment management work of the high-temperature gas cooled reactor can be carried out more efficiently, economically and safely.