Abstract: Fiber bragg grating (FBG), as a new type of sensor, has widely attracted much attention by people.Scholars from all over the world have carried out various kinds of research related to it.This paper mainly discusses the detection of the ultrasonic wave in photoacoustic imaging system by FBG, in which the clear photoacoustic image of pencil lead can be obtained..Besides, because the FBG has a small size and pure optical features, this method can be used in medical endoscopic detection with strong electromagnetic environment.In the future, photoacoustic imaging system combined with FBG has the potential to provide a high quality imaging method.