Abstract:L-7, a bacterium which was able to degrade chlorimuron-ethyl, was isolated from the soil of long term applied with chlorimuron-ethyl by enrichment culture. Base on physiological and biochemical characteristics and 16S rRNA sequence analysis, the strain L-7 was identified preliminarily as Stenotrophomonas sp.. The effect of initial concentration of chlorimuron-ethyl, inoculation amount, temperature and pH on degradation efficiencies was studied. The optimal degrading conditions were: initial concentration of chlorimuron-ethyl 100 mg/L, inoculation amount of 5%, pH 4.0, respectively, under the optimal conditions, the degrading efficiency could reach more than 80% after 5 days at 30°C.