This dissertation mainly discussed the investigation of three different Formosan soft corals, Xenia florida, Cespitularia sp., and Asterospicularia laurae, and also the coral medicinal herb Kadsura philippinensis. Their EtOAc extracts were investigated by chromatography. Forty-three natural products, including twenty- five new natural products were isolated and parts of their biological activities were studied. Xeniolactone A (1), a new skeleton natural product, and xeniolactones B and C (2, 3) were isolated from Xenia florida, together with eight known compounds florlide C, 9-deoxyxeniolide B, xeniolide H, florlides A and G, floridicin, blumiolide B and xeniaoxolane . In the research of soft coral Cespitularia sp.,eighe new compounds inculding four cespitularane-type diterpenes (4