The aim of this study was to obtain nanoparticles and improve solubility of ursolic acid (UA), using supercritical antisolvent process (SAS). The four effects of process variables on drug particle formation during SAS process were investigated. Particles with mean particle size ranging from 139.4 ± 19.4 to 1039.8 ± 65.2 nm were obtained. The UA was characterized by scanning electron microscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy, specific surface area and dissolution test. The XRD analyses showed that the processed UA was amorphous. The processed UA had solubility 4.4 times higher than the unprocessed UA.