The invention provides a method and device for estimating the state of an SF6 high-voltage circuit breaker, and the method comprises the steps: carrying out the estimation of the basic performances and equipment importance of the SF6 high-voltage circuit breaker according to a key characteristic quantity of the SF6 high-voltage circuit breaker; carrying out the estimation of the mechanical performances, electrical performances, insulating performances and accessory performances of the SF6 high-voltage circuit breaker; calculating an overall performance correction factor of the SF6 high-voltage circuit breaker according to the estimation results of the basic performances and the equipment importance; correcting the estimation results of the mechanical performances, electrical performances, insulating performances and accessory performances of the SF6 high-voltage circuit breaker according to the overall performance correction factor of the SF6 high-voltage circuit breaker, and obtaining an overall reference state index of the SF6 high-voltage circuit breaker; and determining a to-be-focused high-voltage circuit breaker and a corresponding maintenance strategy according to the overall reference state index of the SF6 high-voltage circuit breaker. On the basis of an equipment state estimation guide rule, the method proposes equipment reference state analysis, accurately obtains the state of equipment, achieves the ordering of the basic performances of the equipment from the good to the bad, and guides the making of an operation and maintenance decision.