The invention discloses a method and a system for evaluating the health status of major equipment. the evaluating method comprises the steps of S1, receiving major equipment selected by a user, and evoking a fault tree and an evaluation model both corresponding to the selected major equipment out of a database, wherein the fault tree is pre-established based on the corresponding equipment characteristics of the major equipment and the evaluation model is pre-established based on the corresponding operating parameters of the major equipment and the above fault tree; S2, acquiring the fault information of the major equipment and the information of the operating parameters of the major equipment; S3, according to the evoked fault tree and the evaluation model, conducting the calculation and analysis on the acquired fault information and the information of the operating parameters of the major equipment so as to acquire the information of a status assessment result. According to the technical scheme of the invention, the health status of the major equipment can be timely and correctly evaluated, so that a reasonable maintenance strategy can be conveniently formulated. Therefore, the reliability of the major equipment is improved, and the service life of the major equipment is prolonged.