Abstract: Objective: To screen the antibacterial fractions and constituents of Scapharca subcrenata Lischke.Methods: The soft tissues of S.subcrenata was extracted by ethanol.Liquid- liquid extraction with petroleum ether, ethyl acetate, n- butanol and water was used for the separation of ethanolic extract and 4 organic fractions were obtained.The antibacterial activities of the ethanolic extract and organic fractions was evaluated by diameter of inhibition zone ( DIZ) and the minimum bactericidal concentration ( MBC) . The active petroleum ether fraction was separated and purified with silica gel column chromatography, and a sterol mixture was obtained.The compounds in the petroleum ether fraction and the sterols were analyzed by gas chromatography- mass spectrometry ( GCMS) .Results: The antibacterial substances were mainly in the petroleum ether fraction, and 30 compounds were identified by GC- MS, most of which were 1ipids and sterols.Eight compounds were identified by GC- MS from the sterol component, and seven compounds were identified for the first time from S. subcrenata. Conclusion: The antibacterial activities of petroleum ether fraction from S. subcrenata were obvious, and sterol was the major compound of petroleum ether fraction.