A pyrethroids degrading strain qw₅ was isolated from activated sludge.The strain qw₅ was preliminarily identified as Bacillius Licheniformis.The optimum temperture and pH for the aerobic degradation of pyrethroids by qw₅ were 30 and pH7~8.The strain was able to degrade Fenvalerate,Cypermethrin and Deltamethrin by approximately 53.8%,41.2% and 61.7% respect ively within five days.Benaldehyde, 3-phenoxy,the metabolite of Fenvalerate was detected by mass spectrum.The strain was not pathogenic to white mice and sensitive to some commonly used antibiotics.The results from pot and field experiments showed that the strain had obvious effect on the removal of pyrethroids residual in green vegetable.