The authors investigated the degradation features of benzene by strain B6 dominant strain isolated and purified from the petroleumcontaminated groundwater in the northeast of China. Results show that when the initial mass concentration of benzene was 394.36 mg/L, the degradation rate of benzene by train B6 was 82.82% on the third day; ortho 2 cleavage of catechol was the right approach of benzene degradation under the effect of dioxygenase; B6 strain could produce tryptophanase, lipase, amylases, gelatinase, lactase, oxidase, use glucose, lactose, protein, tryptophan, fat, starch, gelatine, polypeptide, cellulose, sulfurcontaining organic compounds, cytochrome C as nutrients, and utilize nitrites and nitrates as electron acceptors in its metabolic process. It was identified that B6 strain was Rhodococcus erythropolis, grampositive bacterium.