A strain that can degrade butyl acetate was isolated from the activated sludge of a sewage treatment plant in Zhejiang Province. It was identified as Acinetobacter modestus by physiology, biochemistry and 16S rRNA, and it was named HYY- 1. The degradation characteristics of butyl acetate were studied with the strains, and the results showed that the strains had a higher degradation effect on butyl acetate under alkaline (pH=8-10) conditions. When the concentration of butyl acetate is 264.75mg/L-1059mg/L, the degradation rate is higher, and the degradation rate of the highest concentration of butyl acetate can reach 100% within 120h. The initial inoculation concentration of the strain has little effect on the degradation efficiency, and the degradation efficiency of different inoculation concentrations can reach 100% within 120h. In addition, the ways of degrading butyl acetate by the strain were speculated from the aspect of degradation products. The study found that the degradation products of the strain were CO2, bacterial biomass, n-butanol and acetic acid, and the proportions of the degradation products were different under different initial butyl acetate concentrations.