Abstract: In order to avoid the interruption of dosing in the nuclear power circulating water treatment system, the purchased high-concentration sodium hypochlorite dosing can be realized by adding a dosing device, and a PLC control system is added, which is connected to the network switch in the original control cabinet through a network switch, and realize real-time data exchange with the original main control system, which not only retains the functions of the original system, but also realizes various process control and interlock protection of the newly added system. As a result, the reliability and stability of the operation of the power plant is improved.