A new method was developed for the determination of aniline and benzidine in environmental water by direct injection and ultrahigh-pressure liquid chromatography(UPLC) with fluorescence detection.Through the investigation of mobile phase,pH value and conductivity of water samples,and filter materials,the optimum conditions were obtained.Under the optimal conditions,water samples were filtered through the microfiltration membrane(0.22 μm，PTFE),and analyzed by UPLC using acetonitrile-3.85 g/L ammonium acetate(25∶75) as mobile phase in 0.8 min.The fluorescence detection wavelengths were set at λex/λem=232 nm/329 nm for aniline and λex/λem=292 nm/383 nm for benzidine.Good linear relationships were obtained in the range of 1.0-100.0 μg/L for aniline and benzidine with correlation coefficients more than 0.999.The relative standard deviations(n=10) of 10.0 μg/L aniline and benzidine were 0.4% and 0.5%,respectively.Recoveries for the method were in the range of 86%-106%.The detection limits(S/N=3) for aniline and benzidine were 0.023 μg/L and 0.024 μg/L,and the quantitation limits(S/N=10) were 0.078 μg/L and 0.079 μg/L,respectively.The method was simple,sensitive and rapid,and could be applied in the detection of aniline and benzidine in environmental water.