The invention provides a method and a device for transformer state assessment based on benchmark state analysis. The method comprises the following steps: basic performance and equipment importance assessment is carried out on transformers according to key characteristic quantities of the transformers; mechanical performance assessment, electrical performance assessment, thermal performance assessment and accessory performance assessment are carried out on the transformers; the comprehensive performance correction factors of the transformers are calculated according to results of basic performance and equipment importance assessment; assessment results of the mechanical performance, electrical performance, thermal performance and accessory performance of the transformers are corrected according to the comprehensive performance correction factors of the transformers to obtain the general benchmark state indexes of the transformers; and the transformers of critical concern and corresponding maintenance strategies are determined according to the general benchmark state indexes of the transformers. According to the invention, equipment 'benchmark state' analysis is put forward on the basis of the equipment state assessment guide rule, an accurate understanding of the equipment state can be achieved, and the purpose of ranking equipment according to basic performance from good to bad and guiding maintenance decision-making is achieved.