Abstract: Residual dynamics and factors affecting degradation of clornamne in different paddy soils are studied in this paper．The results show that the degradation of clomazone answers to the first-order kinetics equation C = C₀e^-kt and its half-life in four kinds of soils is 5．7～22．0d．Through sterilization，clomazone is degraded more slowly than the nonsterilized one．The degradation of clomazone is dependent on the microorganisms and affected by soil prope rties ．temperature．soil moisture and pH value．The distinct negative correlativity exists between the degrada tion speed of clomazone and organic matter content of different paddy soils，and the correlative coefficient is -0．8336．The process of degradation of clomazone is somewhat sped up in a certain degree with temperature increasing，however，the degradation spe edof clomazone at 25℃ behaves faster than that at 35℃ ．With the soil moisture increasing and the addition of lime into sol1．the degrada tion of clomazone will be accelerated ．