According to the characteristics of high hardness, turbidity and alkalinity of raw water in Xuecun gangue Power Plant, 4 000 tons of make-up water is needed for the power plant every day. Only after pretreatment, the turbidity of raw water can be reduced, and the conductivity and hardness can not be reduced. With evaporation, the salt will be continuously concentrated in the water cycle which leads to severe scaling of industrial water cooling system in the whole plant, and seriously affecting the production. Xuecun gangue Therml Power Plant of Jizhong Energy Fengfeng Group Co., Ltd. selects the method of adding quicklime according to the characteristics of the water coming from the mine. The experiment and comparison show that adding lime can significantly reduce the hardness of the raw water. Under the existing water quality and process conditions, the highest hardness removal rate is 34.5%, and the best frequency of adding is 35 Hz. At the same time, it shows that the excessive lime can reduce the hardness removal efficiency.