<p>The influence mechanism of trace Nb on the corrosion resistance of surface corrosion products of high-strength anti-seismic rebar in the simulated marine environment was studied by combining first-principles calculations with corrosion mass loss method, surface analysis, cross-sectional analysis, quantitative analysis, and electrochemical test. The results demonstrated that the addition of trace Nb effectively improved the compactness and stability of surface corrosion layer of rebar, and the corrosion resistance of corrosion layer increased with the increase in Nb content. The beneficial effect of Nb content on the corrosion layer summarized two important key points. Firstly, the addition of Nb was beneficial to promoting the improvement in the structural stability of α-FeOOH, and α-FeOOH structure of solid solution Nb atoms was beneficial to strengthening the fixation of Cl atoms, thus increasing α/(β + γ) ratio, total impedance value, and corrosion potential. Secondly, the formation of Nb oxides can not only repair the corrosion layer, but also play a role in the fixation Cl atoms, resulting in the improvement in corrosion resistance of corrosion layer.</p>