Abstract: In order to obtain the microorganisms degrading nicosulfuron,five strains of microorganisms numbered as YB1,YB2,YB3,YB4 (bacteria),and YF1 (fungi) were isolated by enrichment culture with nicosulfuron as the only source of carbon,nitrogen and energy.All of the microorganisms were cultured in culture medium containing different concentrations of nicosulfuron,then put it in swing bed at 30℃ and shook at 150 r/min for 5 days,detected the concentration of nicosulfuron by HPLC and calculated the degradation efficiency.It was shown that the degradation rates of the five strains of microorganisms were higher in low concentration than in high concentration of nicosulfuron,with YF1 having the highest degradation rate of 80.31％,secondly,YB1 and YB2 having the degradation rate of 78.18％ and 73.72％,respectively,however,YB3 and YB4 having lower degradation rate of 36.82％ and 25.75％,respectively.It was also discovered that YF1 was Aspergillus niger,YB1 and YB2 were Bacillus sp.by primary identification.