Abstract: It was found that in an acetate buffer of pH 5,the color-fading oxidation of bromocresol green by hydrogen peroxide was sensitively inhibited by trace amounts of aniline,and that linear relationship between the intensity of inhibitory action and the concentration of aniline was obtained in the range of 0-45.0 μg·L-1 with a detection limit of 4.30 μg·L-1 of aniline. Based on these facts,a new and sensitive method of photometric determination of traces of aniline in environmental water was proposed. The interferences of NH+4,Fe(Ⅲ) and Pb2+ ions were eliminated by separation of aniline by distillation. The optimum conditions of the method and the kinetic parameters were studied. In the analysis of 3 samples of waste water,RSD′s (n=6) obtained were in the range of 2.35%-3.78%,and recoveries were in the range of 95.8%-103.6%.