It is proposed that ultrasonic wave is introduced into fiber Bragg grating axially in the form of rectangular pulse wave.The mechanism of ultrasonic pulse acting on fiber Bragg grating is analyzed.On this basis,the ultrasonic pulse generator circuit and ultrasonic transducer are designed to drive the stack piezoelectric ceramics with high voltage pulse to generate compression pulse along the fiber axis,and then the pulse amplitude is amplified through the aluminum cone structure matching the acoustic impedance,which is coupled into the fiber grating efficiently.The dynamic reflection spectra of FBG in time domain were collected by CCD imaging method and the spectral variation law in time domain was analyzed.The results show that when the ultrasonic pulse is longer than the length of the fiber Bragg grating,the fiber Bragg grating (FBG) introduced by ultrasonic pulse can shift the spectrum effectively and shift the center wavelength at the moment of pulse action.It provides reference for the combination of ultrasonic pulse and wavelength division multiplexing demodulation technology.