The corrosion behavior of Cu-bearing aged weldable steels with varied Ni levels of 2.5Ni, 2.0Ni and 1.5Ni was assessed via an indoor dry-wet alternating accelerated test, aiming to simulate the tropical marine atmospheric environment, by means of mass loss method, scanning electron microscopy (SEM), X-ray diffraction (XRD), electron probe microanalysis (EPMA) and electrochemical test methods. The findings demonstrate that in the simulated tropical marine atmospheric environment, the corrosion rates of the three experimental steels increase initially, then decrease and finally remain steady. Their corrosion rate decreases with increasing Ni concentration. The steel with 2.5Ni corrodes at a rate that is 25% less than that of 1.5Ni. The rust layer is rich mostly in Ni and Cu. The addition of Ni to the steel will result in the formation of NiFe₂O₄ in the rust layer, which favors the conversion of γ-FeOOH phase to α-FeOOH phase, thus increases the compactness of the rust layer. The higher the Ni content, the more obvious the effect, thereby, the better the protectiveness of the rust layer. The propensity for the free-corrosion potential and the resistance of the rust layer increase with the increasing Ni concentration. Therewith the rust layer can effectively inhibit the anodic dissolution and the transfer of charged particles within the rust layer.