Abstract: The corrosion behavior of X80 steel with defect coating in Yumen soil simulation solution along the "West East Gas Pipeline II" was studied using corrosion immersion and electrochemical impedance spectroscopy. The results show that the defect free coating X80 steel did not show significant corrosion in the simulated solution, while the X80 steel under the defect coating showed significant corrosion. X80 steel with coating defects exhibited typical dual capacitance arc resistance characteristics in simulated solutions. With the increase of soaking time, the corrosion rate of X80 steel in simulated solution showed a trend of first decreasing and then increasing. In the early stage of corrosion, the accumulation of corrosion products led to a decrease in corrosion rate. With the increase of time, localized acidification at the defect site caused coating damage and exposed the fresh metal surface. Then the corrosion was promoted continuously.