Circulating water treatment agent is divided into chemical method and physical method. The cooling circulating water system mainly adopts chemical methods, including water treatment system, dosing system, cleaning system and backwashing system. The hardness and salinity of system make-up water are removed by ion exchange. Add scale inhibitor, corrosion inhibitor and bactericide to the combined circulating water, and regularly clean and backwash the system to form a complete set of water treatment technology.