Three thermophilic bacteria were isolated from the crude oil contaminated soil samples gathered from Yaerxia oil reservoirs of Yumen oilfield in Gansu Province. According to their 16S rRNA gene analyses, and the physiological properties, the isolated XS1 was identified as Brevibacillus sp; and the isolated XS2 and XS3 were identified as Geobacillus pallidus. The three isolates could degrade crude oil and had effective emulsification activity. All the isolates can grow at a high temperature, with the optimal growth temperature of XS2 being 60℃, and have a wide adapt-ability to pH, in the range of 5.5—9.5. NaCl concentration has no obvious effect on the growth of three strains. Meanwhile, XS2 has an effective emulsification activity; and the emulsification activity has no apparent change at 100℃ and under 20% salinity conditions. The analysis of chromatogram characteristic changes of crude oil during biodegradation process shows that the strain XS2 can degrade not only the light-weight components of crude oil, but also its heavy-weight components, it enhances the fluidity of crude oil, and the quality of crude oil is also improved. It will have a good prospect in microbial enhanced oil recovery.