Abstract: During long-term operation of indirect cooling circulating water systems in thermal power plants,problems such as continuous increases in total hardness and total alkalinity,accumulation of suspended solids,scaling,corrosion,and microbial growth commonly occur.Conventional treatment methods,including chemical dosing and periodic blowdown,suffer from large fluctuations in water quality,high chemical consumption,and significant water waste.To address the deterioration of circulating water quality in a 660 MW indirect cooling unit,a bypass softening treatment process integrating pretreatment,softening,decarbonization,and polishing treatment was established,together with an automatic monitoring and precise regulation system.The optimized process parameters and control strategies suitable for unit operation were determined.After implementation,the total hardness of circulating water was stably controlled below 50 mg/L,total alkalinity was maintained below 30 mg/L,suspended solids were reduced to ≤2 mg/L,and the system concentration ratio remained stable at 5.5–6.0.The proposed technology effectively mitigates scaling,corrosion,and microbial proliferation in indirect cooling circulating water systems,reduces blowdown volume and chemical consumption,and achieves long-term stable water quality control,providing an effective solution for refined circulating water treatment in large-scale thermal power units.