A bacterium capable of utilizing fenpropathrin as sole carbon source was isolated from activated sludge collected from wastewater treating system of a pesticide manufacturer. This bacterium was identified as Sphingomonas sp. according to its physiological & biochemical analysis and the similarity analysis of its 16S rDNA sequence (GenBank Accession No. DQ177525). This bacterium could degrade 99.8% of 20 mg/L fenpropathrin in 24h. The optimal pH and temperature for the degradation were 7.0 and 30 degrees C, respectively. The degradation speed was related positively to initial inoculum size. The enzyme distribution experiment showed that the degrading-enzyme in the bacterium was endoenzyme.