Abstract: The disbondment of highly insulating triple-layer polyethylene (3PE) coatings on buried steel pipelines can induce "cathodic protection (CP) shielding", and the resulting localized corrosion has long been a critical challenge in oil and gas pipeline industry. This study investigates the potential distribution characteristics and corrosion behavior of X80 steel under disbonded coatings in various soil environments using a simulated coating disbondment experimental setup, aiming to provide guidance for analyzing corrosion evolution and formulating protection strategies in disbonded regions. A self-developed adjustable disbondment simulation device was employed to examine CP potential distribution at different positions within the disbondment. Combined with characterization techniques including scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The CP potential distribution along disbondment direction and localized corrosion features have been studied and analyzed in four typical soil environments: coastal saline soil, inland saline-alkali soil, red clay, and meadow soil. The key findings demonstrate: CP potential shifts positively as the extending of disbondment zone. Effective CP protection mainly concentrates around the coating defects, then the CP potential decays rapidly along disbondment zone until reaching near-free corrosion state, here the CP current would be shielded. The CP potential distribution and effective protection range are influenced by liquid film thickness within disbondment zone and soil salt content (resistivity). High-salinity, low-resistivity coastal saline soil facilitates better CP current penetration. Restricted ion diffusion/migration within confined disbondment space significantly affects spatial distribution of potential/current. Localized corrosion predominates in coastal saline soil and red clay environments, whereas uniform corrosion occurs in inland saline-alkali soil and meadow soil. Corrosion rate in disbonded regions substantially exceeds that at open coating defects..