The reducing substances in water include various organic compounds, nitrites, sulfides, ferrous salts, etc., but the most important ones are organic compounds; Therefore, chemical oxygen consumption is usually measured（COD, as a comprehensive indicator for measuring the content of organic matter in water, plays an important role in water quality monitoring. The higher the COD value, the more severe the pollution of organic matter in the water bodyMultiple water quality standards are correctThe COD value has been restricted. In order to eliminate the tedious operation of preparing reagents and testing processes for users, and improve detection efficiency, this COD prefabricated tube reagent is launched based on two standards: HJ 828-2017 and HJ/T 399-2007.