Abstract: The degradation of crude oil with different microbes in Qinghai Oilfield is studied for evaluating the performance of microbes and discussing the mechanism of microbiology enhance oil recovery.In the laboratory condition,three different bacteria can use the Qinghai crude oil as the sole carbon source in appropriate nutrition condition.After incubate six days at 37℃,the surface tension of medium is reduced.The surface tension of the medium of bacteria B is reduced to 47.4 mN/m.The crude oils treated by bacteria are analyzed with gas chromatograph(GC).The results of GC show that the lighter compounds of crude oils are decreased,but the long chain hydrocarbon compounds is increased.The rate of pr/nC17 of the crude oil degraded by bacteria B is increased from 0.542 to 3.262,while the rate of ph/nC18 is increased from 1.351 to 10.748.So the bacteria B have great potential in microbial enhanced oil recovery.