Abstract: The relationships were analyzed for the spherical confocal Fabry-Perot interferometer between free spectral width, half-width of transmission lines and fine optical parameters of swith the cavity length and radius curvature of spherical mirror theoretically. According to the characteristics and requirements of laser ultrasonic testing, a laboratory spherical confocal Fabry-Perot interferometer was designed. According to the interferometer parameters chosen and the specific structural form, the scanned sawtooth wave of the interferometer was got, which showed the success of non-contact laser ultrasonic measurement.