GB/T 11892-1989 is a standard in the field of water quality testing, focusing on the determination of permanganate index. The permanganate index reflects the content of reducing substances that can be oxidized in water bodies and is an important indicator to measure the degree of pollution of water by organic matter. The standard elaborates on the two determination processes of acid method and alkaline method, covering the collection and treatment of water samples, the reaction with potassiumhy permanganate and subsequent titration operations, and clarifies the calculation method of the results. The method specification is suitable for various types of water samples, providing data support for water quality monitoring and pollution assessment, and helping to maintain the health of the water environment.