<p>To investigate the galvanic corrosion behavior of a copper (Cu)-304 stainless steel curved surface coupling system in a chloride-containing acidic environment, wire beam electrode (WBE) technology was innovatively integrated with dynamic electrochemical monitoring. The approach enabled a systematic analysis of how the geometric characteristics of a curved surface and variations in cathode area jointly influence local corrosion dynamics. A series of flat and curved (curvature radius: 3 mm) Cu WBE models, along with cathode areas of varying diameters (ϕ0.3–0.9 mm), were constructed. By coupling these with in situ current distribution mapping, electrochemical impedance spectroscopy, and polarization curve analysis, it was revealed that the curved surface geometry significantly enhanced chloride ions/proton mass transport and facilitated the dynamic breakdown of passive films, thereby elevating the local corrosion intensity index to 2.9 times that observed under flat-surface conditions. Further investigations demonstrated that a moderate cathode size (ϕ0.7 mm diameter) effectively optimized the interfacial microenvironment, markedly suppressed the anodic dissolution rate (total current density reduced by 28%). And it increased the breakdown potential of the stainless steel passivation film, enhanced the self-repairing ability of the passivation film. This study, for the first time, elucidates the dynamic mechanisms underlying the synergistic regulation of galvanic current distribution by surface curvature and cathode area, offering critical theoretical insights for the corrosion-resistant design and life prediction of dissimilar metal joints with complex geometries in aggressive environments.</p>