As offshore oil and gas resources are extensively explored, the risers of the floating production storage and offloading (FPSO) system will confront substantial corrosion challenges. To meet the demand for corrosion protection status monitoring, this study proposes a corrosion protection monitoring system that can operate at a sea depth of 300 m. It is primarily composed of a pressure-resistant, watertight enclosure, an integrated plug-in electrode system on the Outer shell and a data collection module. The system continuously monitors the electrode potential, collecting, processing, and analyzing data to offer a direct representation of the corrosion and cathodic protection condition of the subsea riser support structure, which is crucial for guaranteeing the system’s safety.