In this paper, the failure mode, the failure influence and fault criticality analysis of the circuit breaker spring operating mechanism are analyzed based on the historical fault data of the breaker in the Xiamen an-dou substation and the analysis of the structural function characteristics of the breaker operating mechanism. According to the conclusion of the analysis, the closing coil current, vibration and acoustic signal are determined as the monitoring parameter of the monitoring system. The limitation of single or single source sensor to the operation state of circuit breaker is overcome by combining data from multi-source sensor.