Abstract: The effects of pressure on the yield of flaxseed oil in the extraction process of flaxseed oil by supercritical CO2 extraction technology were studied under the constant-pressure extraction conditions（21, 28,35 MPa） . The lipid composition and the content of each component of flaxseed oil extracted by supercritical CO2 extraction technology and traditional pressing method were detected by GC-MS. The results showed that the maximal yield of flaxseed oil extracted for 120 min under 35 MPa was 35.65%, which could meet the actual application demands. The fatty acid composition in the flaxseed oil extracted by supercritical CO2 extraction was basically same with that by traditional pressing method. The content of linolenic acid in the flaxseed oil extracted by supercritical CO2 extraction was slightly higher.