A high power, high frequency air ultrasonic transducer used to generste air ultrasonic Phase grating is fabricated. The laser ultrasonic acousto-optic deflection has been observed clearly by using a displacement-sensitive detector and a particularly ptepated acoustic coupler setting at a proper place in front of the acoustic radiating surface of the transducer to increase the interference of acoustic field and to decrease the divergence angle of acoustic radiation. It can be applied to measure the parameters of the air vortex flow field in wind tunnel test.