In order to provide references for the evaluation and selection of deep-sea coating，a study was conducted on four dual-layer epoxy coating systems by using deep-seaenvironment simulation experiments（64 ℃，15 MPa）to investigate the performance variations of epoxy coatings under deep-sea conditions. Pull-off adhesion tests and cathodic disbondment tests were carried out on both the initial coatings and those subjected to the deep-sea simulation experiment to analyze the effects of the deep-sea environment on the basicproperties of the coating. Additionally，the water absorption，electrochemical impedance spectroscopy（EIS）， and surface morphology of the coating were examined after variousdurations of immersion in normal-pressure water and the deep-sea simulation experiment. Theresults showed that，after deep-sea pressure tests，the coating could still effectively adhere to the steel surface，but their impedance and corrosion resistance significantly decreased. Finally， considering the practical application of anti-corrosion systems in deep-sea environments，this article highlighted the inadequacy of conventional cathodic protection design standards fordeep-sea conditions and suggested that deep-sea cathodic protection should take into accountthe actual resistance of the coatings used on steel structures.