Abstract: This study utilizes wet/dry cyclic corrosion testing combined with corrosion big data technology to investigate the mechanism by which chloride ions (Cl⁻) influence the corrosion behavior of 650 MPa high-strength low-alloy (HSLA) steel in industrially polluted environments. The corrosion process of 650 MPa HSLA steel occurred in two distinct stages: an initial corrosion stage and a stable corrosion stage. During the initial phase, the weight loss rate increased rapidly owing to the instability of the rust layer. Notably, this study demonstrated that 650 MPa HSLA steel exhibited superior corrosion resistance in Cl-containing environments. The formation of a corrosion-product film eventually reduced the weight-loss rate. However, the intrusion of Cl⁻ at increasing concentrations gradually destabilized the α/γ* phases of the rust layer, leading to a looser structure and lower polarization resistance (R_p). The application of corrosion big data technology in this study facilitated the validation and analysis of the experimental results, offering new insights into the corrosion mechanisms of HSLA steel in chloride-rich environments.