The oscillating hot air that generated by a pulse combustor can be used to atomize and dry liquid materials. It has many advantages, such as low operation cost, high drying quality, and simple structure of the dryer. A small Helmholtz pulse combustor was used in this research. An optical analyzer was employed for measuring the mean diameters of atomized droplets and droplets size distribution. The feed rate and viscosity of liquid material, frequency of oscillating hot air are the main factors affecting the atomizing properties. The experimental results indicated that the uniform droplet size distribution could be obtained under the conditions of a low feed rate, high-frequency pulsating flow and moderate viscosity.