Abstract: Abstract: This paper briefly introduces the chemical supervision work of Huaneng Tongchuan Zhaojin Coal Power Co., Ltd. during unit maintenance and the optimization and improvement of feedwater and furnace water treatment methods in recent years. Chemical supervision during unit overhaul is a comprehensive inspection of the quality control and supervision of water, steam and oil during the operation of the unit as well as the effect of corrosion during decommissioning. Through supervision and inspection, it evaluates whether the feed water and furnace water treatment methods used in the operation of the unit are reasonable, whether the sampling is representative, whether the water and steam quality control and oil quality control are effective, and is an overall inspection of all chemical supervision of the previous operation cycle. It is important to ensure the safe and reliable operation of the unit and prolong the service life of the equipment.