The extraction of oil from soybean with supercritical CO 2 is studied. Under the condition of a pressure of 20~30MPa and a temperature of 308~323K, the influence of pressure, temperature, solvent mass flow rate and the method of pretreatment on the fraction of yield oil is investigated. The results show that the best operation condition is 30MPa, 313K, and soybean is pressed to slices. The solvent mass flow rate only affects on the rate of extraction, and has no influence on the fraction of yield oil.