To ensure the water saving and operation safety of units at the same time, the optimal treatment scheme and operation condition of circulating cooling water were sought for. According to the characteristics of circulating cooling water taking soft water as supplement, the performance of four scale and corrosion inhibitors was studied by limit carbonate alkalinity method, weightloss method and dynamic simulated test. In the dynamic simulated test, “1/2Ca2++JDM”value which replaced the traditional ΔA value was used to adjust the sewage discharge in the circulating water system, and the corrosion of the concrete of cooling tower immersed in the circulating water with high SO42- content was observed. Being soaked in circulating water for 20days, the morphology of specimens remained unchanged, and the SO42- content of the solution was stable. The results show that QJ has excellent corrosion and scale inhibition performance, and is suitable for the circulating cooling water system taking soft water as supplement.It is feasible to prevent scaling in circulating water system by controlling “1/2Ca2++JDM” value, and SO42- shows no significant erosion on cement and aggregate in concrete when circulating water is of high cycle of concentration.