A bacterium designed as GF-1, capable of utilizing lambda-cyhalothrin as the sole carbon source was isolated from activated sludge collected from wastewater treating system of a pesticide manufacturer. GF-1 was identified as Bacillus sp. based on its surface features, physiological and biochemical characteristics, and analysis of its 16S rDNA. GF-1 could degrade 85% of 100 mg/L lambda-cyhalothrin in 72 h. The optimal pH and temperature for degradation of lambda-cyhalothrin were 7.0 and 30℃ respectively. The degradation rate was correlated positively with the initial inoculation rate. The rate of degrading lambda-cyhalothrin in soil increased after inoculating GF-1. The strain lost its ability to degrade lambda-cyhalothrin when the plasmid was removed by acridine orange and heating. This observation indicated that the plasmid of GF-1 was relative to the ability to degrade lambda-cyhalothrin.