The present invention relates to a compound of Antrodia camphorata used to inhibit HBV, in particular to an extract, 4-hydroxy-2,3-dimethoxy-6-methyl-5(3,7,11-trimethyl-dodeca-2,6,10-trienyl)-cyclohex-2-enone which is isolated from Antrodia camphorata, and its use in inhibiting HBV effectively. The cyclohexenone compound according to the present invention showed cytotoxicity on HBV-secreting human hepatoma cell line HepG2 2.2.15, decreased synthesis of HBV particles, further inhibited synthesis of HbsAg and HbeAg effectively to achieve the goal of HBV inhibition.本發明係關於一種用於抑制B型肝炎病毒之牛樟芝環己烯酮化合物,尤其是關於一種由牛樟芝萃取物中所分離出之4-羥基-2,3-二甲氧基-6-甲基-5(3,7,11-三甲基-2,6,10-十二碳三烯)-2-環己烯酮(4-hydroxy-2,3-dimethoxy-6-methy-5[3,7,11-trimethyl-do deca-2,6,10-trienyl]-cyclohex-2-enone)並可有效抑制B型肝炎病毒。本發明中,牛樟芝環己烯酮化合物對於能分泌B型肝炎病毒之人類肝癌細胞株HepG2 2.2.15係具細胞毒性,並可降低B型肝炎病毒顆粒之生成量,且可有效抑制B型肝炎表面抗原(HbsAg)以及B型肝炎外套膜抗原(HbeAg),藉以達到抑制B型肝炎病毒之目的。