To study the chemical constituents contained in Acorus calamus.The chemical constituents were separated and purified by various chromatographic methods including silica gel, ODS, HPLC and Sephadex LH-20, and their structures were identified on the basis of analysis on spectroscopic data.Ten compounds were separated from A. calamus and identified as 1beta, 4beta, 7alpha-trihydroxyeudesmane (1), bullatantriol (2), teuclatriol (3), threo-1', 2'-dihydroxyasarone (4), erythro-1', 2'-dihydroxyasarone (5), (+)-de-4'-O-methyleudesmin (6), (+)-de-4'-0-methylmagnolin (7), (+)-eudesmin (8), (+)-magnolin (9) and beta-sitosterol (10), respectively.Compounds 1-2,4-9 were separated from this plant for the first time. Specifically, compounds 1-2,6-9 were obtained from Acorus genus for the first time.