GB/T 12157-2007 Specifies the determination method of dissolved oxygen in industrial circulating chilled down water and boiler water. It introduces a variety of measurement methods, such as electrochemistry probe method, indigo sodium disulfonate Colorimetry, etc., and clarifies the scope of application of each method. From sample collection, storage, to specific measurement operations, including instrument calibrating, reagent addition and other steps, are described in detail. By accurately measuring the dissolved oxygen content, it can effectively monitor water quality, prevent equipment corrosion, provide a key basis for the rational treatment and use of industrial water, and is widely used in water management of industrial production.