Abstract: The isolating property of pipeline coating for buried steel pipeline is an index to evaluate the quality of coating. The measurement method of coating decides the degree of confidence of parameters measured. Through a site measurement on CP parameter of Shaanxi-Bejing gas transmission pipeline and Anshan-Dalian oil pipeline, the paper analyzes the measurement results with three common measurement methods used (DCVG, multi-frequency method, variable frequency method) and evaluates the site results and CP parameters obtained in daily care.