Abstract: At present,the Condition-based Maintenance（CBM） of circuit breakers widely adopts the planned power outage mode both at home and abroad,therefore there exist possibilities of failure to detect the latent defects of the circuit breaker in time,which results in power grid accidents caused by circuit breaker failures. To this end,we invented a circuit breaker fault warning device composed of mechanical vibration measurement terminal, electric field strength measurement terminal,loop current measurement terminal and intelligent diagnosis modules,and developed a circuit breaker health status quantitative evaluation system consisting of health evaluation and intelligent grading modules. The field verification of the device and system was conducted and the results suggest that the invented fault early warning device of circuit breakers can successfully realize the non-invasive fusion collection of high-voltage switch vibration,electric field,and circuit current signals during operation and greatly reduce the complexity and installation risk of the installation process of the measuring equipment,and realize the early warning of 17 kinds of faults in3 categories of circuit breakers. The developed system realizes real-time evaluation of the short-term and long-term health of circuit breakers and reduces the cost of circuit breaker inspection.