Six strains named SY1 to SY6 were isolated from oil-polluted soil. The degradation tests of oil by our isolates were carried out under still-reaction-bottle-aeration and shaking-aeration conditions. The co-metabolic characteristics of two co-substrates (ethanol and glucose) and inorganic ions on the biodegradation of oil by our isolates were also studied. The results show that oil can be degraded by the six isolates effectively. The degradation ability of strains is enhanced due to co-substrates added. The enhanced roles of glucose are stronger than ethanol to SY1 and SY5; while the enhanced roles of ethanol are stronger than glucose to SY3.And the enhanced roles of glucose and ethanol are similar to SY2, SY4 and SY6. Inorganic ions, such as Ca2 + Fe2 +, Mg2+, etc, could promote the degradation ability of strains and improve the growth of strains. The degradation effects of mixed strains were inferior to that of single strain. After five days, the degradation rate of SY3 was worst, which was 65.7%. In the mixed strains, there were only 11 groups’ degradation rates greater than that of SY3, and other 46 groups’ degradation rates were less than that of SY3.