Abstract: 【OBJECTIVE】The biological characteristics of organophosphorus pesticide-degrading bacterium, Enterobacter cloacae will be studied in this paper to explain the mechanism of degrading .【METHOD】The growth curve, physiological characteristics of E. cloacae were observed. Meanwhile, the suitable cultural medium, growth temperature, pH value, shaking speed, cultural volume were tested to determine the best cultural conditions for E. cloacae. And the endure and utilization abilities of E. cloacae to Dimethoate, Methamidophos, Dichlorvos and Trichlorfon were measured.【RESULTS】E. cloacae started logarithmic growth after 3 hours, and could utilize a great part of carbon-containing compounds and grow under nutrition-lacking condition. Its suitable growth temperature and pH were 10-43℃ and 6-12, respectively. Its degradation to Dimethoate, Methamidophos, Dichlorvos and Trichlorfon was base on the existence of certain nutrition materials.【CONCLUSION】E. cloacae had fast growth speed and could survive under nutrition-lacking condition, which meant that it was a bacterium suitable for degradation of organophosphorus pesticides in soil and water.