Abstract: A new method was developed for the determination of copper oxychloride residue in different water matrix using high performance liquid chromatography with pre-column derivatization. The sample was acidified and then pretreated with pre-column derivatization method using sodium diethyldithiocarbamate before injection. The chromatographic separation was performed on a C18 reversed phase column,using methanol and water as the mobile phase and quantified by UV-vis spectroscopy at the wavelength of 305 nm. The results showed that the calibration curve was linear within the range of 0.06-2 mg/L. The limit of detection (LOD) and limit of quantification (LOQ) of this method were 0.02 mg/L and 0.06 mg/L, respectively. The average recoveries in three different water matrix at three spiked concentration levels of 0.06, 0.2 and 1 mg/L ranged from 85% to 108% with the relative standard deviations (RSD) from 2.2% to 14%. The substances in all different water matrix did not appear to interfere with the determination. This method is simple, accurate and reliable, which is suitable for the rapid determination of copper oxychloride in water.