The impressed current cathodic protection system (ICCP) is used to protect the underwater parts of offshore steel structures from seawater corrosion. Its working principle is to provide DC current through the potentiostat. The positive pole of the power supply is connected to the auxiliary anode, and the negative pole is connected to the steel structure. The circuit is formed by seawater to conduct cathodic polarization of the steel structure. The reference electrode is used for monitoring and detection, so that the protected steel structures are always maintained at the best protection potential and protected from seawater corrosion. The system can automatically adjust the required protective current with the change of external conditions. It has been widely used in thousands of ships and marine facilities, and has achieved remarkable results.