Abstract: Since the cathodic protection system in Renqiu Initial Pump Station has been put into operation, output current of potentiostat is continuously on the high side.In the light of this problem, analysis and evaluation on CP protective potential and coating performance along pipeline are carried out.Results show that the performance of coating in pipe sections at Stake K001~K010 is deteriorated, and the coating is aged.By means of PCM inspection, PCM experiment near anode groundbed and metering PCM with potentiometer, inspection and evaluation on PC system of the pipeline are made, and it is concluded that failure of insulating joint is the main cause of this problem.