The work aims to study the galvanic corrosion mechanism of anodized 5A06 aluminum alloy/1Cr18Ni9Ti stainless steel coupling and the effect of Cl– concentration on its corrosion behavior, It provides a basis for the corrosion and protection of aluminum alloy in different service environments. The galvanic corrosion experiments of anodized 5A06 aluminum alloy and 1Cr18Ni9Ti stainless steel were set at different Cl– concentrations. The effect of Cl–concentration on the corrosion behavior of anodized 5A06 aluminum alloy was discussed, according to the analysis of the change law of the corrosion current, the characterization of the surface corrosion morphology and composition, and the electrochemical test. With the increasing of corrosion time, the galvanic current fluctuated zigzag and gradually decreases and then tended to be stable. The variation of galvanic current with Cl– concentration was 3.5%>5%>2%>6.5%>8%>0.5%，When the Cl– concentration was 3.5%, the maximum galvanic current was 16.56 μA/cm2. In the process of galvanic corrosion, the corrosion products on the surface of 5A06 aluminum alloy anodic oxide film block the pitting pits, hinder the further reaction of Cl– with substrate in solution. The anodic oxide film shows a cyclic process of destructing-repairing-destructing; Cl– can not only promote the dissolution of anodic oxide film of aluminum alloy, increase the sensitivity of galvanic corrosion of aluminum alloy, but also reduce the concentration of dissolved oxygen in solution, which help to inhibit the occurrence of anodic reaction. When the concentration of Cl– is less than 3.5%, the effect of promoting dissolution is greater than that of inhibiting reaction, and when the concentration of Cl– is more than 3.5%, the effect of inhibiting reaction is more obvious than that of promoting dissolution. Therefore, The galvanic corrosion rate increases first and then decreases with the increase of Cl– concentration。