The strain C7 was isolated from activated sludge,which was identified to be Ochrobacterum sp..It was cultured with endosulfan as the sole carbon source.The degradative ability of C7 to endosulfan was determined by HPLC,and the degradative rate of endosulfan at 50 mg/L was above 90.2% within 8 days.The optimum conditions for endosulfan degradation by C7 were 25% of total inoculum size,30℃ and pH 7.0.