Abstract: The inside and outside flow fields of ultrasonic atomization nozzle for dust suppression were studied through numerical calculation and experimental test methods. Results show that the pressure distribution of jet nozzle inlet and ultrasonic oscillation cavity is larger according to the pressure and velocity vector distribution of the internal flow field of the nozzle. The liquid speed after ultrasonic oscillation cavity is reduced, and the vortex is formed within the nozzle. With the increasing of jet pressure, droplets D₅₀ showed an obvious decreasing trend. With the increase of ralative distance from jet nozzle to ultrasonic oscillation cavity, droplets D₅₀ decreased first and then increased, and droplets speed increased and then slowly decreased. The most optimal location for ultrasonic oscillation cavity is 3.5 cm.