Abstract: A strain of bacterium PF32,capable of utilizing parathion-methyl as the sole carbon source for growth,was isolated from the sludge of a pesticide plant after taming and enrichment. Strain PF32 was identified as Stenotrophomonas sp. on analysis of its phenotype,physiological-biochemical characteristics and the similarity analysis of its 16S rRNA sequence. Strain PF32 could degrade about 99% of 100 mg/L parathion-methyl at 24h after inoculation.The optimal pH value and temperature for parathion-methyl degradation by PF32 was 7.0 and 30℃,respectively.The degradation rate was positive to initial inoculum rate.Strain PF32 also could degrade other organophosphorus pesticides such as phoxim,fenthion,fenitrothion,triazophos and chlorpyrifos quickly.