<p>Poly (4-styrene sulfonate sodium) (PSSS), a biocompatible macromolecular corrosion inhibitor (CI) for the galvanic corrosion (GC) between ADC12 aluminum alloy (AA) and copper, was developed through experiments, theoretical calculations and simulations of a micro GC model. The experimental results demonstrated that PSSS significantly suppressed the cathodic processes of the AA. Under coupling condition, it was selectively adsorbed on the surface of the AA through a combination of physical and chemical adsorption, conforming to the Langmuir adsorption model. Due to the formation of a CI film on the surface of the AA by PSSS, the current density was reduced, and the GC was suppressed. Its corrosion inhibition efficiency at 300&#xa0;mg·L⁻¹ was 79.1%. The multi-physics simulation results indicated that the electrode deformation of the AA was the most severe at the coupling point, and the addition of PSSS slowed down. The difference between the lowest unoccupied molecular orbital energy and the highest occupied molecular orbital energy of the PSSS structural unit was 2&#xa0;eV. Furthermore, molecular dynamics simulation results revealed that PSSS was adsorbed on the surface of the AA in a flat manner, with the adsorption energy of − 303.194&#xa0;kJ·mol⁻¹.</p>