The influence of chloride or sulphur dioxide on the corrosion behavior of copper tube in the air-conditioning system was studied using scanning electron microscope (SEM),energy dispersion spectrometer (EDS) and cyclic polarization techniques. The results showed that the corrosion of copper tube are mainly caused by the SO2-4- and Cl- ions in the circulating water, and the former is mainly responsible for the general corrosion of the copper tube whilst the latter for the pitting corrosion. The different influences of SO2-4- and Cl- ions on the corrosion type of copper tube may be attributed to that the radius of SO2-4- ion is much larger than that of Cl- ion. Meanwhile the results also indicated that SO2-4- inhibits the pitting corrosion caused by Cl- and Cl- inhibits the general corrosion initiated by SO2-4- due to their competitive adsorption on the copper matrix.