Abstract: In order to study enzymatic degradation characteristics of nicosulfuron by Alcaligenes faecalis ZWS11, extracellular, intracellular crude enzymes and cell debris were extracted from strain ZWS11 by methods of acetone precipitation, ultrasonic fragmentation and centrifuge separation. The enzyme activity of the extraction from ZWS11 was systematic studied under laboratory conditions. The results showed that the enzyme activity was high when the ratio of fermentation broth and acetone was 1:3 (V/V). At the presence of extracellular, intracellular crude enzymes and cell debris, the average degradation rates of nicosulfuron (24.9 μmol/L) were 87.4%, 16.9% and 17.4%, respectively. The degradation capability was significantly different between the extracellular enzymes and intracellular crude enzymes or cell debris (P60%) were achieved when the pH ranged from 4.0 to 9.0, and temperature ranged from 35℃ to 70℃, which demonstrated that the degrading enzymes had a broad pH tolerance and a good thermal stability. The activity of degrading enzymes could be inhibited in the presence of different concentrations of SDS and PMSF. The results provided scientific basis for further studies on the large-scale production of nicosulfuron-degrading enzymes and the bioremediation of nicosulfuron-contaminated soil.