JQL4-5 (Sphingomonas sp.), a fenpropathrin-degrading strain isolated from soils exposed to repeated pesticides contamination, was used in this work to study factors affecting its degrading capacity of fenpropathrin in soil microcosms. In sterilized soil, the degradation rates of fenpropathrin by JQL4-5 were faster than those in unsterilized soil. Various factors, including soil pH, temperature, initial fenitrothion concentration, and inoculum size influenced its degradation efficiency. The addition of 10(6) CFU x g(-1) was able to degrade varying concentrations (10-200 mg x kg(-1) soil) of fenpropathrin over a temperature range of 20-40 degrees C and pH range (6.5 - 7.5). The results indicated that strain JQL4-5 has potential use in bioremediation of fenpropathrin-contaminated soil.