Abstract: The influences of different pH values and Cl^- concentrations on the corrosion resistance of Cu-Ni-Al alloy in different service conditions in engineering are investigated by X-ray diffractometer, scanning electron microscope, static full immersion corrosion test and electrochemical test. The results show that when pH=3, it is difficult to form corrosion product film on the surface of the alloy. When pH=3 and pH=12, Cu₂(OH)₃Cl is difficult to attach to the surface of the alloy. When pH is between 6 and 10, a bilayer structure of corrosion product films forms on the surface of the alloy, which has a protective effect on the metal material. The surface layer is the loose (Cu₂(OH)₃Cl) layer, and the internal layer is the dense Cu₂O layer. Due to the different electrochemical cathode reactions during the corrosion, the cathodic reaction is promoted under acidic condition, while it is inhibited under alkaline condition. Therefore, as the pH value of the corrosive medium increases, the Cu-Ni-Al alloy material is more likely to passivate in the corrosive medium, and the average corrosion rate of the alloy will gradually decrease. As the concentration of Cl^- in the corrosive medium increases, the formation of the Cu₂O film on the surface of the Cu-Ni-Al alloy will be inhibited, which can weaken the protective capability of the Cu₂O film for the internal alloy, and accelerate the average corrosion rate, therefore, the corrosion resistance of the alloy decreases.