GB/T 17131-1997 is a water quality testing standard. Gas chromatography and CG are used to determine 1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,2,4-trichlorobenzene. These chlorobenzene-containing compounds are often caused by industrial pollution and threaten water quality safety. The standard details the whole process of water sample collection, extraction and enrichment of target substances, injection of Gas Chromatograph, separation and Detector detection by Chromatography Column, and determination of content through Retention time and Peak area. The instrument conditions, reagent preparation, operation steps and result calculation are clearly specified. The method is accurate and efficient, which helps water quality monitoring and provides strong technical support for the prevention and control of chlorobenzene-containing pollution in water bodies.