Abstract: By installing sound pressure sensor, vibration accelerometer and other devices in the operating mechanism of the circuit breaker, the signal waveform during the action of the circuit breaker is extracted, and then the acoustic and vibration waveform characteristics and variation rules of the circuit breaker under different states are obtained by using special software. The waveform characteristics corresponding to the abnormal state of the operating mechanism are summarized, and the feasibility of on-line monitoring the operating state of the operating mechanism of the circuit breaker is verified.