The property changes of urine crystallites of six cases of calcium oxalate stone formers before and after taking medicine were comparatively studied using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, nanoparticle size analyzer, and transmission electron microscopy (TEM). The results showed that the urinary pH increases after taking medicine (before taking 5.87±0.51, after taking 6.23±0.74.) Before taking medicine the main components of urine crystallites were uric acid, calcium oxalate monohydrate (COM) and biphosphate. The types and quantities of urine crystallites after taking medicine were less than that of before. The average size of urine crystallite before taking medicine was (579±326) nm, and it reduced to (404±338) nm after taking medicine. After taking medicine the zeta potential was also decreased to (-7.29±4.16) mV from (-4.28±2.55) mV. The decrease in zeta potential is beneficial to preventing urinary crystallites deposition. The edges and corners of urine crystallite were sharp with significant aggregation before taking medicine, while they became blunt and less aggregation after taking medicine. The analysis of the property changes of urine crystallites of calcium oxalate stone patients before and after taking medicine by using modern equipments has important clinical significance to the clinical prevention and treatment of urinary stones.