Abstract: The dynamics of dissipation and half-life of nicosulfuron with different water content in soil, and the effect of water content in soil on the dissipation of nicosulfuron was studied. Soil samples were extracted with V (acetonitrile):V(phosphate buffer solution)=1:4, and the residue of nicosulfuron was determined by high performance liquid chromatography with UV detector (HPLC-UV). Linear correlation of nicosulfuron was 0.999 9 with concentration between 0.25-4 mg/L. The results of fortified experiment showed that the recovery was 91%-106%, with relative standard deviation (RSD) between 5.4%-9.5% on the fortified level of 0.05, 0.25 and 1.25 mg/kg. The limit of detection (LOD) for nicosulfuron was 0.012 mg/kg, and the limit of quantification (LOQ) of the method was 0.04 mg/kg. Water content in soil has only a little effect on the half-life of nicosulfuron when water content was below 50%. The half-life increased first and decreased later when water content was over 50%. The dissipation rate of nicosulfuron was the highest with 60% and 90% water content in soil, the half-life was 19.7 and 18.6 d, respectively.