Abstract: With the large-scale application of new energy power generation such as photovoltaic and wind power, the demand for a regional DC distribution network with a high proportion of DC access in industrial parks, application of DC distribution system is increasing. DC distribution technology has many advantages, which has attracted more and more attention from industry and academia, higher requirements are placed on its core equipment, low voltage DC circuit breakers. In order to realize the detection of the arc-extinguishing chamber of medium and low voltage DC circuit breakers, this paper proposes a DC circuit breaker detection technology based on optical fiber EFPI sensor. The structure, sensitivity and center frequency analysis of the sensor are mainly discussed and tested. The proposed optical fiber sensor can be used for discharge detection of medium and low voltage DC circuit breakers.