Abstract: Chemical oxygen demand is one of the main indicators for judging organic compound pollution in water bodies and for controlling the total amount of pollutants discharged into the water environment in our country.The classic Chemical oxygen demand test uses chemical oxidants,such as potassium dichromate and potassium permanganate,to break down the results into the amount of oxygen consumed,ultraviolet UV254 is also used to determine the absorption of organic pollution of water.These methods are simple and easy to implement,but they are time-consuming and laborious.At present,through modern science and technology and the development of Chemometrics on-line monitoring and remote sensing inversion methods to measure COD,huge amounts of monitoring data can be integrated,more effective and objective assessment of the extent and scope of organic pollution of water bodies.