[Objective]To research on the biological characteristics of Silybum marianum (L.) Gaertn. seeds. [Method] With the S. marianum seeds in three cultivation sites as the test materials, seed size and 1000-grain weight were measured; semi-thin section was adopted; and the germination situation of seeds under different temperatures were redearched. [Result] Seed was composed of embryo and scarfskin. Scarfskin consisted of five layers; the outwards four layers were peel, and the inwards was testa. Seed embryo developed well without endosperm, fat was the main storage material of cotyledon. The suitable temperature for seed germination was 25℃ and few seeds had dormancy phenomenon. [Conclusion] The basic biology data of S. marianum seeds were accumulated, which provided theoretical basis for the cultivation, classification and pharmacognostic identification of S. marianum seeds. [Objective] To research on the biological characteristics of Silybum marianum (L.) Gaertn. Seeds. [Method] With the S. marianum seeds in three cultivation sites as the test materials, seed size and 1000- grain weight were measured; semi- thin section was adopted; and the germination situation of seeds under different temperatures were redearched. [Result] Seed was composed of embryo and scarfskin. Scarfskin consisted of five layers; the outwards four layers were peel, and the inwards was testa. Seed embryo developed well without endosperm, fat was the main storage material of cotyledon. The suitable temperature for seed germination was 25 ° C and few seeds had dormancy phenomenon. [Conclusion] The basic biology data of S. marianum seeds were accumulated, which provided theoretical basis for the cultivation, classification and pharmacognostic identification of S. marianum seeds.