Abstract: The liquid jet atomization is widely applied to chemical engineering and aerospace. Atomization performance has a significant influence on the chemical reaction and mass transport. Air-blast atomization is an effective method to obtain fine droplets, especially for the viscous liquid jet atomization. How to obtain deserved size droplets has been a hot area of atomization research. The effects of bubbles in the liquid jet on the air-blast atomization of viscous liquid were investigated using the Malvern laser particle size analyzer. The glycerol-water solution with Ohnesorge number (Oh) of 0.0346—0.407 was used as the liquid phase, and air as the gas phase. Experiments with various coaxial gas velocities (94.8—142 m/s) and liquid jet velocities (0.29—1.21 m/s) were conducted to study the influences of inner bubbles on the droplets size. It was found that at low Oh , the droplet diameter decreased with the volumetric flow rate of aerating gas for the low liquid jet velocity, and the droplet diameter increased with the volumetric flow rate of aerating gas for the high liquid jet velocity; the droplet diameter increased with the volumetric flow rate of aerating gas at high Oh . A model was deduced to delineate the variation trend of the droplet diameter. We compared the predictions of this model with experimental results and found that the relative deviations were less than ±5%.