• Effect of the reduction of Cu 2+ on the corrosion behavior and mechanism of Al-2%Zn coating in NaCl solutions was reported. • Impact of reduction reaction of more Cu 2+ is more pronounced, resulting in a negative shift in corrosion potential and a decrease in cathodic Tafel slope. • General corrosion morphology changes to localized as the concentration of Cu 2+ increases to 110 μg/L. • The corrosion products film plays a shielding effect when the concentration of Cu 2+ is below 50 μg/L. A layer of Al-2%Zn coating was sprayed on 5083 aluminum alloy substrate. The effect of Cu 2+ on the corrosion behavior and mechanism of the coating in 3.5 wt.% NaCl solution was investigated using electrochemical techniques and surface analysis. The experimental results show that when the concentration of Cu 2+ is lower than 50 μg/L, an inductive semicircle appears in the electrochemical impedance spectrum at the beginning of immersion. When Cu 2+ concentration is 110 μg/L, no inductive semicircle was detected, indicating that the degradation process was promoted in the presence of Cl - . XPS and EDS analysis shows that Cu are formed in the corrosion process. With the increase of Cu 2+ concentration, the reduction of Cu 2+ to Cu gradually plays an important role in the cathodic reaction, while the reduction of oxygen is relatively weak, leading to the reduction of the cathodic slope and the negative shift of the mixed potential. The corrosion products film on the surface will cover the corrosion pits and plays a shielding effect due to the active dissolution of the coating. When the concentration of Cu 2+ exceeds 50 μg/L, this effect disappears and the surface morphology changes to obvious local corrosion morphology, including flaking and cracking.