The corrosion behavior of pure copper in simulated acid rain of different pH was investigated by using electrochemistry impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) as well as SEM. The results show that the impedances of pure copper in simulated acid rain of different pH present various characteristic, indicating the different corrosion mechanisms. The results of XPS show that cuprous oxide only form on the surface of pure copper in pH=3 solution and cupric oxide only exist in pH=5 solution as well as the mixture of both oxides appear in pH=6 solution. The diffusion of O₂ and H⁺ through solution may influence the corrosion process of pure copper. In low pH solution, the diffusion of dissolved oxygen through double electric layer is the rate-controlling step due to the promotion of the hydrogen ion. With increase of pH value, the oxygen of depolarization effect mainly control the corrosion process of pure copper without the effect of hydrogen ion.