Abstract: Compared to the as-received X80 steel with original microstructure,the corrosion behavior of X80 steel heat treated by water quenching and air cooling was studied by Tafel polarization and electrochemical impedance spectroscopy (EIS).The morphology of corrosion products was analyzed by FE-SEM.The experimenal results showed that,after corrosion for 20 days in simulated soil solution of Dagang,the corrosion rate of X80 steel with original microstructure was lower than that with heat treated microstructure.The difference of microstructure and the compactability of corrosion products led to the different corrosion resistance.