<p>Corrosion in harsh marine atmospheric environments poses a critical challenge to the durability and service safety of main cable steel wires in cross-sea suspension bridges. To elucidate the underlying micro-corrosion mechanisms, the dissolution behavior of pearlite in 86MnSi suspension bridge cable wire was investigated in a solution simulating the South China Sea marine atmosphere. A multimodal characterization approach was employed, including surface morphology analysis (SEM, EBSD, TEM, AFM), phase analysis (XRD), microchemical analysis (EPMA), and electrochemical measurements (EIS, CPP). The results indicate that within the lamellar pearlite structure, ferrite acts as the anode and undergoes preferential dissolution due to its high dislocation density and stress concentration, while cementite serves as the cathode, forming a micro-galvanic couple. In the early corrosion stage, cracking and spalling of TiN inclusions initiated pitting corrosion. As dissolution progresses, the continued dissolution of ferrite results in a distinct lamellar corrosion morphology, with cementite acting as a residual skeleton. Furthermore, short-range diffusion and rapid aggregation of solute atoms (e.g., Cr, Mn, C) at grain boundaries lead to precipitate formation. This process induces chromium depletion in the adjacent matrix, significantly exacerbating local corrosion and ultimately causing the detachment of grain boundary precipitates, which subsequently develop into corrosion pits. This study elucidates a corrosion mechanism for bridge cables in marine atmospheres that is driven by micro-galvanic couples, initiated by inclusions, and exacerbated by grain boundary precipitation. The findings provide a theoretical basis for the selection and life cycle assessment of high-corrosion-resistance bridge steels.</p>