The invention discloses an on-load tap-changer state monitoring method and system based on information fusion, and belongs to the technical field of electric power, and the method comprises the steps:obtaining an effective vibration signal of an on-load tap-changer in a to-be-detected operation state; obtaining a phase point distribution track and a vectorized phase point distribution coefficientof the effective vibration signal in a phase space by adopting a phase space reconstruction technology; solving the membership degree of the to-be-measured operation state corresponding to each fuzzyset by using the vectorized phase point distribution coefficient and a multi-dimensional Gaussian membership function; and selecting an operation state corresponding to the maximum membership degreeas a to-be-tested operation state; according to the invention, the vectorized phase point distribution coefficient under each operation state is used as a characteristic information base of each operation state; the three-dimensional Gaussian fuzzy set membership function capable of simultaneously processing characteristic values of multiple channels is established, a normal state and multiple fault states can be effectively identified, and compared with an existing monitoring method based on a single channel, the information utilization rate is high, the anti-interference capability is high,and particularly, the identification rate is greatly improved.