In order to investigate the droplet distribution of air-assisted orchard sprayer, a model for Hardi LB—255 air-assisted sprayer was developed based on CFD technology. The 2-D boundary and the model variables were defined to correspond to the tested sprayer. The trajectory of air-assisted droplets and the distribution of droplets in different layers were simulated. The relative errors of simulated results could show the droplet distribution accurately with the range less than 240 cm from the fan. 