Crude oil is a kind of organic matter, relatively insoluble in water, which seriously affects its bioavailability.Some bacteria are found to be able to produce biosurfacant, which can emulsify the crude oil and enable the bacteria to adhere to the hydrophobic surface of the oil very strongly, thus enhancing bioavailability of the crude oil in the environment.It is reported that bacteria with hemolytic circle in the blood plate show emulsifying activity.Therefore strains of the bacteria were isolated from the petroleum contaminated soil through enrichment culture in BH medium with crude oil from Jianghan as the sole carbon source and hemolytic activity assay on blood agar plates.Nine strains with high degrading and emulsifying ability were isolated.Strain X13-1 was found at the top of the list of the bacteria with emulsifying ability reaching 80% and 75% at 1h and 24 h respectively.OD_600nm of the culture fluid with paraffin as the sole carbon source was used to indirectly measure petroleum-degrading abilities of bacteria.The OD_600nm of strain X13-1 was up to 0.566.Besides its emulsifying ability and petroleum-degrading ability, strain X13-1 was chosen for ulterior research.Cell wall composition, morphology, metabolism Biolog Microstation Identification System and the sequence analysis of 16S rDNA fragment amplified from total DNA of bacterium X13-1 were used to identify the strain of bacterium.The results show that the bacterium is G^- and bacilliform.SIM (Similarity) in Biolog to typical Acinetobacter calcoaceticus is 0.826 and 16S rDNA sequence homology with typical A.calcoaceticus in the genebank is 97%.To sum up the above-described characters, it can be concluded that strain X13-1 is likely to be an A.calcoaceticus.