Abstract: As a medical plant with a long history, the Usnea species of lichen are widely distributed in China. However, the research about its chemical composition and activity is rare, delayed, and the basic data accumulation is weak, which restricts its further development and utilization.The primary metabolites polysaccharide(lichenan, isolichenan, galactomannan, and heteropo-lysaccharide) and fatty acids, and secondary metabolites(single benzene ring derivatives, depsides, depsidones, and benzofuran) of the Usnea species of lichen are reviewed in this article.The research progress of the bioactivity of lichen polysaccharide and lichen acid are introduced. Lichen polysaccharides have functions of antioxidation and antitumor; and lichen acids have functions of insecticidal, antibacterial, anticancer, antitumor, antioxidation, antivirus, antiinflammatory, liver-protecting, detoxication, and enzyme inhibition.