Abstract: To study the influence of dorsal pressure difference on the atomization characteristics of a pressure swirl nozzle, the spray cone angle, Sauter mean diameter, speed of the spray particles, and their radial and axial distributions were experimentally studied.Results show that the spray particles and spray cone angle increase with increasing dorsal pressure difference, while Sauter mean diameter decreases.The atomization parameters vary less than 5% when the dorsal pressure difference is higher than 0.30 MPa.The spray droplet velocity decreases with the increase of the axial distance, while the Sauter mean diameter increases and then drops off with increasing axial distance when the dorsal pressure difference is fixed to 0.30 MPa.The rises in Sauter mean diameter and spray cone angle occur with increasing radial distance along the radial direction.