Through inoculation of isoproturon-degrading bacteria into soils different in environmental conditions, characteristics of the degradation of isoproturon in the soils by strains Sphingobium sp. YBL1, YBL2 and YBL3 were studied, and effects of soil type, temperature, soil moisture, inoculation dosage and carbon/nitrogen source on the degradation were analyzed. It was found that strains YBL1, YBL2 and YBL3 could efficiently degrade isoproturon (>80%) in Magan soil (pH 6.7), but could not in Red soil within 24 hours. The degradation rates of isoproturon in Magan soil by these three strains were positively related to soil moisture (10%~40%) and temperature (16~37°C). When the dosage of inoculation was less than 10⁵ CFU per gram soil all these three strains were unable to degrade isoproturon in soil in 24 hours after incubation. Supplementation of glucose could enhance degradation of isoproturon in Magan soil by these strains, while the addition of NH₄NO₃ could do reversely.