Abstract: A rapid and direct analytic method has been established for the determination of nitrobenzene and aniline in environmental water samples by Ultra Performance Liquid Chromatography (UPLC). The mixture of 900 μL water and 100 μL acetonitrile was filtered through a microfiltration membrane (0.2 μm, organic). The UPLC analysis program has been improved by using a BEH phenyl separation column, filled with 1.7 μm BEH particles, and the mobile phase used acetonitrile ammonium acetate. Nitrobenzene and aniline were detected respectively at the ultraviolet (262 nm) wavelength and fluorescence (λ_ex/λ_em=280 nm/340 nm) respectively. The whole analysis program took only 1.1 min. The linear range of nitrobenzene and aniline were 0.485-4850 μg/L and 0.495-1978 μg/L, respectively. The detection limits of the methods were 0.194 μg/L and 0.099 μg/L, respectively, and the correlation coefficients were both above 0.995. The recoveries of nitrobenzene in three concentration levels of 9.70 μg/L, 194 μg/L and 1940 μg/L were 98.3%-101%, and the relative standard deviation was in the range of 1.11%-2.03%. The recoveries of aniline in three concentration levels of 9.89 μg/L, 198 μg/L and 1978 μg/L were 98.6%-104%, and the relative standard deviation was in the range of 0.75%-5.85%. Compared with the traditional liquid chromatography analysis methods, this method is suitable for the determination of nitrobenzene and aniline in groundwater, surface water and other water samples, with the advantages of being simple, rapid, sensitive, highly efficient, with a wide linear range and less sample and reagent consumption.