Abstract: In order to solve the problem of wide fluctuations of circulating water concentration rate in some power plants, Huaneng Dezhou Power Plant is taken as an example to analyze the relationship between the concentration rate and the conductivity of the cooling water Based on the analysis and with the combination of the DCS control system, the control system for circulating water concentration rate stabilization is established. The application results indicate that the system conducts real-time monitoring accurately, is easy to operate, effectively buffers the considerable fluctuation of circulating water concentration rate caused by heavy blowdown and ensures the steady operation of circulating water with high concentration rate.