The power supply is needed for traditional automatic fire alarming system when it is running.Electrified alarming sensors are prone to cause a fire where there are combustive and explosive things.Fiber bragg grating(FBG) and distributed FBG sensors reduce fire risks greatly.This paper studies the performance of a fiber bragg grating and a fiber bragg grating sensor,based on the physical working of a fiber bragg grating and a fiber bragg grating sensor.