Abstract: The heavy metal elements in crude oil samples pretreated by dry ashing were determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The primary parameters of ICP-OES, such as, wavelength for element analysis, radio frequency (RF), atomization pressure, type and concentration of acid solutions were optimized using standard solutions prior to analyze the practical samples. The accuracy and precision of the method were investigated by analyzing the results of crude oil samples. Under the optimum conditions, the recoveries of Fe, Ni, Cu and V determined by this method are 90.3%~108.0%, which is within the scope of standard (90%~110%). The detection limit of the method and the relative standard deviations are lower.