The work aims to study corrosion prevention mechanism of synthesized waterborne PHEA-DOPA containing dopamine pendant functional groups in waterborne epoxy anticorrosive coatings. A PHEA-DOPA adhesive polymer was successfully prepared based upon continuous aminolysis reactions among polysuccinimide, ethanolamine and dopamine. Structure of this adhesive polymer was characterized by FTIR, 1HNMR and UV-Vis spectrophotometer. Furthermore, protective properties and mechanism of the waterborne epoxy coating containing PHEA-DOPA were investigated by EIS, scanning electron microscope (SEM), quartz crystal microbalance with dissipation monitoring (QCM-D) and Raman microspectroscopy. The results of FTIR, 1HNMR and UV-Vis measurements demonstrated that the PHEA-DOPA polymer was successfully synthesized. The EIS and SEM results indicated that the addition of PHEA-DOPA could significantly improve protection properties of waterborne epoxy coatings. The evidences of QCM-D and Raman microspectroscopy demonstrated that the DOPA group in PHEA-DOPA structure had strong adsorptive complex effects on Fe3+, and could generate in soluble [Fe(DOPA)3]3+ complexes on the surface of carbon steel and inside the coatings, which inhibited dissolution process of Fe and improved coating density. Addition of PHEA-DOPA adhesive polymer can significantly improve protective properties of waterborne coatings.