Abstract: The form mechanism of ultrasonic grating is discussed and the acoustic-optic effect is Naman-Nathdiffraction in ultrasonic grating experiment in liquid base on the distinguish standard of acoustic-optic effect types.The diffractive stripe azimuth of acoustic traveling wave and acoustic standing wave are determined by the same diffractive equation, and the intensity of diffractive stripe is determined by the value of J^2m（v）. Finally, the distriburing characteristic of diffractive stripe and diffractive intensity are given.

Key words: acoustic-optic effect, Naman-Nath diffraction, diffractive stripe, ultrasonic grating