Ultrasonic atomization has been used for the production of high quality powders for soldering and soldering pastes. This research is to study the production of SAC305 powder employing an ultrasonic atomizer. Effects of operating parameters: melt temperature, melt feed rate, amplitude of acoustic wave and oxygen content in the atomizing vessel, on the median particle size, the particle size distribution and the morphology of the atomized powder have been investigated. Experimental results indicated that the median particle size and the particle size distribution tended to be better, i.e. smaller and narrower, respectively, with increasing melt temperature owing to the decrease of viscosity and surface tension at higher temperatures. With decreasing melt feed rate and decreasing vibrating amplitude, the median particle size decreases and the particle size distribution gets more uniform since the thickness of melt film on the probe is thinner at a lower feed rate thus droplets can easily take off from the vertices of small waves. Under natural atmosphere, most particles were found to form irregular, teardrop and ligament shapes. However, the atomized powders become rounder with decreasing oxygen content in the atomizing vessel.