Rhodococcus erythropolis LSSE8-1 is a newly isolated biodesulfurizaion strain from the soil of Chishui gas field, Guizhou Province, China. The analysis of its metabolism product shows that the strain is a kind of biocatalyst able to oxidize dibenzothiophene (DBT) to 2-hydroxydi- phenyl (HBP), and therefore the sulfur in DBT is selectively removed. By using DBTO2 (dibenzothiophene 5,5-dioxide) as substrate, both DBT and HBP are found in the culture, which shows that the reaction from DBT to DBTO2 is reversible in the cell. While using 0.5 mmol/L DBT as control, 0.01-0.4 mmol/L DBTO2 shows poisonous effect to the cell, which will explain why there is no DBTO2 accumulation in the process of biodesulfurization. After treatment by lysozme, the plasmid DNA of the strain is isolated by alkaline method to be used as the template of PCR reaction. Three dsz gene fragments of 1.3, 1.0 and 1.2 kb respectively were amplified. Each fragment is ligate with PGEM-T vector, and cloned into E. coli. DH5α. The clone DNA is sequenced and the result shows that dsz related genes are highly conservative. The identities of dszA and dszB with respect to IGTS8 are 100%, and the identity of dszC with that of IGTS8 is 99%.