Abstract: SCAL indirect air-cooling unit has become a trend in the development of thermal power in northern China. With the large-scale promotion of this type of unit, the problems of abnormal water quality and material corrosion facing the system have gradually become prominent, which has become a major problem troubling the chemical operators of the system. Based on the analysis of the structure and corrosion status of SCAL indirect air-cooling system, A water quality improvement scheme for Xinjiang A power plant was developed. The bypass water purification equipment installed in the system, including iron remover, filter and Ion purifier, and after the water quality treatment is qualified, the special iron and aluminum dual-effect corrosion inhibitor for SCAL indirect air-cooling is added to the system, and the purpose of water purification and water quality optimization is finally achieved. In the end, good application results have been obtained.