The refractive index of a medium will change periodically when ultrasonic wave propagates in it, and the medium can serve as a grating with light propagating perpendicularly to the propagating direction of ultrasonic wave. When the light and ultrasonic wave propagate in the same direction through the medium, the medium can be considered as one-dimensional photonic crystal, one-dimensional ultrasonic photonic crystal (1DUSPC). With plane wave method, it is proved that the 1DUSPC shares the same bandgap characteristic of conventional multilayered one-dimensional photonic crystal, and the bandgap can be modulated by adjusting the wavelength and amplitude of ultrasonic wave. New method is provided to control light by the study.