Abstract: The cathodic protection system plays an important role in the pipeline corrosion control. The paper analyzes the problems existing in the cathodic protection system of Donghuang second pipeline. By inspecting and invesatigating the cathodic protection potential of the outlet pipeline sections in Donghuang and Zhangling pump station as well as Weifang pipeline section, the paper points out that the main causes of the insufficient cathodic protection for these sections include that the underground metal pipe joints can not ensure the relative space distance between pipes; the pipe joints have not been insulated perfectly during construction, which makes the protective coating damage gradually; the poor quality of construction makes the protective coating deteriorative severely; and the solar energy and AC power are used simutaneously in some cathodic protection stations along the pipeline, while the AC power is not available, which makes the power supply reduced and cathodic protection potential declined. Some suggestions are given in the light of the problems above mentioned.