Abstract: An improved bioassay method was used for the study of the effects of soil microbial,soil temperature and soil moisture content on the degradation rate of Chlorsulfuron in Gleyed sandy loam soil(Taihu Lake paddy soil)with the pH value of 5.46.The results of the study showed that:(1)the degradations of Chlorsulfuron in different treatments were all coincident with the first-order kinetics equation;(2)the degradation rates of Chlorsulfuron in non-sterilized soils were obviously higher than in sterilized soils;(3)the degradarion rates of Chlorsulfuron increased with the increasing of soil temperature and soil moisture content.Its half-lives were between 0.7 weeks and 5.8 weeks.