A novel method called indirect-mode jet pulse spray (JPS) for producing mono-sized droplets was proposed. The jet is stimulated to spray into uniform droplets under the effect of gas pulses, which is generated by employing a distribution mechanism where the periodical switch-on between the gas inlet duct and outlet duct is achieved by rotating. The influence of the processing parameters on the droplet size and its distribution was evaluated using paraffin wax. It was shown that the high jetting pressure and rotational speed favors the uniformity of droplets at a relatively wide range of jetting velocities, suggesting that the indirect JPS system is very stable and robust against the change of working conditions. In the case of P=0.04 MPa and n=350 rpm, most uniform droplets with an average diameter of about 520 mu m and a CV of 3.3-4.2% were obtained. A model based on the gas pressure was developed, giving consistent results with the experiments. The optimum experimental results can be well explained by the Weber instability model. The indirect-mode JPS process has excellent size uniformity, materials flexibility and process stability, permitting great potential for broad applications. (C) 2011 Elsevier Ltd. All rights reserved.