Abstract: Aiming at the problems of uneven spatial distribution and excessive noise of the hydrodynamic ultrasonic atomization nozzle, the influence of the resonant cavity of the ultrasonic atomization nozzle on the atomization characteristics was studied by numerical simulation combined with physical experiments, the oscillation characteristics of the resonance cavity were calculated, the near-field characteristics of atomization were photographed, as well as the average particle size of the droplets and the noise sound pressure level of the nozzle were measured. The results show that for the target nozzle, the pressure oscillation frequency of the resonator in huff and puff mode and non huff and puff mode is determined by the nozzle pressure ratio and geometry, respectively. In the huff and puff mode, the increase in the depth of the resonant cavity will lead to the decrease of the pressure oscillation frequency, which will easily lead to excessive noise of the nozzle, while the too small depth will lead to the low flow rate of the expansion airflow at the cavity opening. The inner diameter of the resonant cavity has little effect on the oscillation frequency, but it will lead the uneven droplet distribution and the lower pressure amplitude. The distance between the nozzle and the cavity affects the sound pressure level, and the average nozzle Sauter diameter is inversely proportional to the sound pressure level.