Abstract: Sainfoin （Onobrychis viciifolia） is perennial legume forage and is honored as ＂grass queen＂ due to its high nutritive value and good palatability. It has strong resistance to cold and drought and is widely cultivated around the world. Reports on feeding value, diseases and cultivation techniques of sainfoin are common, but literatures on its secondary metabolites are still limited. We systematically reviewed the differences in content and structure of condensed tannins from sainfoin with different varieties and phenological phases. Furthermore, we elaborated the roles of condensed tannins from sainfoin in ruminant nutrition regulation, with emphasize on its effect on digestion and absorption of nutrients, production performance, occurrence of frothy bloat and gastrointestinal parasites infection in ruminant animals.