Abstract: A type of strain with crude oil degradation and emulsification characteristics was screened and separated from the formation water in District Liuzhong, Karamay oilfield, which should belong to Ochrobactrum according to the characteristics of physiology and biochemistry and 16SrDNA sequence analysis. Experimental study shows that the optimum pH value, temperature and salt tolerance for the bacteria growth are 6~9, 25~37 ℃ and 0~5%, respectively. The crude oil is the sole carbon source, the emulsification index of the strain fermentation liquor reaches 52% and steps into a stable stage after 66 h, which can consume the saturated hydrocarbon, aromatic hydrocarbon and light components in crude oil and then the relative content of saturated hydrocarbon in crude oil decreases from 68.00% to 53.73%, the relative contents of aromatic hydrocarbon, non-hydrocarbons and asphaltene increase from 11.04%, 14.10% and 6.86% to 12.44%, 24.81% and 9.02%, respectively; w（C21-）/w（C22+） and w（C21+22）/w（C28+29） reduce from 1.41 and 2.35 to 0.88 and 0.44, respectively; Pr/nC17 and Ph/nC18 increase from 1.53 and 1.70 to 13.43 and 35.00, respectively. The crude oil is degraded by the strain effectively, which provides possibilities for its further application in field oil displacement test and contaminated soil restoration.