The strain A-3 which could use acetochlor as the sole nitrogen source was isolated from soils contaminated with acetochlor and the sludge of pesticide factory by enrichment culture. The strain was identified as Ensifer adhaerens according to the results of morphology, physiology,and the phylogenetical analyses of 16S rRNA sequence. It was observed that the degradation rate of acetochlor by strain A-3 was 33.6% after 10 days culture at the concentration of 10 mg/L. The composition of the culture could affect the growth of A-3 and the degradation of acetochlor. The growth and degradation ability of strain A-3 were different with the different carbon sources. The strain had the strangest growth capability with the D600 value of 0.55, but the degradation rate was only 9.4% when using sucrose as carbon source. However, the strain A-3 had the highest degradation rate up to 29.2%, although the D600 value was only 0.3 when using glucose as carbon source. When the NaCl concentration was 0.5%, the strain A-3 grew best and had the highest degradation rate of 35%, but when the NaCl concentration was higher than 7%, the growth of A-3 was inhibited and the degradation rate was reduced to 2.6%. The results showed that the strain A-3 could degrade acetochlor effectively and the growth and degradation process was affected by environmental media, and the degradation of acetochlor could be controlled by changing the composition of the culture.