In order to study the efficiency of regional microorganisms on the degradation of crude oil，and ensure the oilfield microorganism and membrane system running smoothly of oily sewage treatment in Yanchang oilfield，six oil degradation bacteria were isolated from oil-contaminated farmland in Wuqi county of Shaanxi province. The growth and degradation characteristic of the six strains were studied through morphological observation，physiology biochemistry experiment，molecular biological techniques（16SrDNA） and GC-MS. The results showed that six oil degradating bacteria included P1 （Microbacterium oxydans），P2（Ochrobactrum intermedium）， P3 （Alcaligenesfaecalis）， P4 （Brevibacillus laterosporus）， P5 （Stenotrophomonas） and P6（Pseudomonas aeruginosa） . After cultivating and domesticating about seven days，the degradation rate of P1～P6 to crude oil was 83.47%，81.60%，85.30%，81.11%，90.58% and 93.16%，respectively. GC-MS analysis results showed that the degradation effect of strains on long carbon chain hydrocarbon was remarkable. At the same time，they all produced a certain amount of surface active substances in the process of degradation，and the maximum decline of surface tension of fermented liquid substrate was 53.19%.