Abstract: An investigative result is obtained through analysis on the pipeline coating, operational parameters of potentiostats and pipe body in LuNing Pipeline (Shandong-Yizheng Oil Pipeline). It is considered that the aged coating results in disbonding, which shields the cathodic current to make the pipe under the disbonded coating in corrosion state. In the paper, the protective measures in repairing the disbonded coating, overhauling the coating and installing sufficient CP devices, which can effectively elongate the service life of pipeline, are present.