Cathodic　disbonding　of　three　layer　polyethylene　(3LPE)　anticorrosive　coating　under　alternating　dry　wet　and　full　immersion　environments　is　now　a　serious　problem　associated　with　oil　and　gas　pipelines.　In　this　study,　under　such　specific　environment,　electrochemical　impedance　spectroscopy　(EIS)　technology　was　used　to　study　the　process　and　mechanism　of　cathodic　disbanding　behavior　of　broken　3LPE　anticorrosive　coating　in　3.5%　NaCl　solution.　The　dry　wet　cycle　involved　two　steps　of　12　h　immersion　followed　by　12　h　drying　process.　The　results　showed　that　broken　3LPE　anticorrosive　coating　exhibited　a　starting　potential　of　-1.28　V　(vs.　SCE)　(-1.20　V　(vs.　CSE))　under　full　immersion　environment.　The　impedance　characteristic　of　broken　3LPE　anticorrosive　coating　exposed　to　alternating　dry　wet　environment　was　similar　to　that　under　full　immersion　environment:　the　impedance　of　anticorrosive　coating　first　increased　and　then　decreased;　however,　the　value　of　impedance　under　dry　wet　process　was　significantly　less　than　that　under　full　immersion　process.　Dry　wet　circulation　significantly　accelerated　the　corrosion　reaction;　moreover,　anticorrosive　coating　failure　rate　was　also　significantly　faster.