Abstract: In order to accurately diagnose the fault of circuit breaker according to its condition monitoring data, a fault diagnosis method of circuit breaker based on improved dynamic time warping algorithm was proposed. The method combines Sakoe-Chiba window with traditional dynamic time warping algorithm, takes opening/closing coil current as analysis object, and extracts potential fault information of the circuit breaker opening/closing mechanism, provides basis for condition maintenance of circuit breaker. Current acquisition circuit of opening/closing coil of breaker was designed, and the effectiveness of the proposed method was verified through actual current signal sampling and analysis.