Abstract: A pneumatic atomizing nozzle operating based on the shear effect was proposed. The nozzle structural parameters which affected the atomization quality were experimentally investigated. Three kinds of air-injection nozzles with diameters of 8.0, 9.0 and 10.0 mm were devised. Tap water served as the working medium, the laser particle size analyzer and a laser Doppler velocimeter were used to test the atomization performance. The effects of air-injection nozzle diameter and air flow rate on ato-mized particle diameter and velocity distribution of atomization droplets were described. Relationships between droplet diameter and velocity were quantified and analyzed. The results show that at the same air flow rate, the nozzle with the air-injection nozzle diameter of 10.0 mm is responsible for the highest droplet velocity and the smallest droplet diameter. With increasing air flow rate, the droplet velocity increases and droplet diameter decreases. As the axial distance from the nozzle outlet increases, droplet diameter decreases first and then increases, and droplet velocity increases first and then decreases. For an air-injection nozzle diameter of 10.0 mm, the droplet velocity exhibits a bimodal distribution at the axial distance of 50.0 mm from the nozzle outlet and the lowest velocity arises near the nozzle axis. At an axial distance of 200.0 mm from the nozzle outlet, the droplet velocity reaches maximum at the nozzle axis.