A bacteria strain X-4 capable of degrading atrazine was isolated from the activated sludge from the wastewater treating system of an atrazine manufacturer. It was preliminarily identified as Arthrobacter sp. according to its physiological & biochemical characteristics and the analysis of its 16S rRNA gene sequence. This strain could use atrazine as sole carbon and nitrogen source, and degrade 95.7% of 100 mg/L atrazine within 42 h. The optimal pH and temperature for the degradation were 30 °C and pH 7.0, respectively. Strain X-4 could tolerate many kinds of heavy metals, which showed its potential in treating the co-contamination of atrazine and heavy metals. The atrazine-degrading related genes of strain X-4 were the combination of trzN, atzB and atzC.