Abstract: Based on computational fluid dynamics （ＣＦD） method, we used automatically generate hybrid grid and two-phase flow fluid cavitation turbulent model to carry out the numerical simulation research on unsteady of pipe flow pattern of cavitation Hartmann type ultrasonic atomization nozzle. Simulation results reveal the ultrasonic atomization nozzle type pipe flow cavitation mechanism and the flow characteristics of cavitation bubble, predict the cavitation of ultrasonic atomization nozzle position and degree. The cavitation intensity of internal nozzle and nozzle mouth lateral is larger, and there is no cavitation phenomenon in resonant cavity, which just plays a role of crushing effect of cavitation bubble. The influence of air volume fraction and cavitation intensity was lower after the inlet pressure was greater than 3 MPa.