Abstract: Silybum marianum seed from five production regions were tested as raw materials on physicochemical properties. Then physicochemical properties, fatty acid compositions (full sample and Sn-2 position), and tocopherols in Silybum marianum seed oil were also analyzed and compared. Results showed that crude fat and crude protein contents had extremely significant difference among Silybum marianum seeds from different regions, and the crude fat content was 17.33%-25.54%. The degree of difference in physicochemical properties followed the order of peroxide value > acid value> saponification value> color and refractive index. 8 fatty acids including linoleic acid (44.74%-56.93%), oleic acid (21.36%-32.75%), palmitic acid (8.36%-9.60%) and stearic acid (4.81%-6.23%) were detected in Silybum marianum seed oil as the main constituents, wherein unsaturated fatty acid content exceeded 77%. Fatty acid compositions in Silybum marianum seed oils from different regions were basically the same. Oleic acid (25.52%-42.07%) and linoleic acid (57.93%-74.47%) were their characteristic Sn-2 position fatty acids, and the samples with higher Sn-2 position fatty acid content were from Hebei and Shaanxi. Tocopherols were the main antioxidant in oils and fats. Only α-tocopherol was detected in the Silybum marianum seed oil with the contents of 466.89 mg/kg to 563.43 mg/kg. The contents of α-tocopherol in Silybum marianum seed oil decreased in the following order: Hebei > Guangxi > Anhui > Shaanxi > Heilongjiang.