Incubation test on the degradation dynamics of Abamectin in soil showed that the half-life of its non-biodegradation plus microbial biodegradation, non-biodegradation, and microbial biodegradation was 34.8, 277.3 and 49.9 d, respectively, and its degradation in soil was mostly by microbes. A dominant bacterium which could effectively degrade Abamectin was isolated from test soil, and identified as Stenotrophomonas maltrophilia by 16S rDNA. The crude enzyme extracted from the dominant bacteria had a Michaelis-Menten's constant 6.78 nmol x ml(-1) and a maximum rate 81.5 nmol x min(-1) x mg(-1).