The fatty acid composition and trans fatty acid contents of Oleum Camelliae samples extracted by different extraction methods and at different refining stages were determined by gas chromatography,using a polar 100m capillary column CP Sil-88 and flame ionization detection.Fatty acids were identified by comparing them with the standards and quantified by area normalization method.Oil extracted by Supercritical Carbon Dioxide (SFC) was detected to have 25 kinds of fatty acids,and 14 of them were not previously reported in other literature.Meanwhile,it was discovered that the oil extracted by direct expression and hexane extraction has 20 and 21 kinds of fatty acids respectively.Different refining stages appear to have no significant effect on fatty acid composition.