To discover novel and bioactive secondary metabolites is a main mission for natural product researchers. Soft corals of the genus Sinularia were proved to yield a wide variety of secondary metabolites including sesquiterpenoids, diterpenoids and steroids. In the thesis, the chemical examinations on the organic extracts of the soft coral Sinularia capillosa (collected at Dongsha Islands) resulted in the isolation of ten secondary metabolites (1¡V10) including five new secondary metabolites (1¡V5) and five known metabolites (6¡V10). The new secondary metabolites included one new tetraprenylbenzoquinone (1), two furanobenzosesquiterpene (2, 3), one furanosesquiterpene (4), and a novel sesquiterpene (5). The known metabolites included an acid-substituted furanosesquiterpene (6), two furanobenzosesquiterpenes (7, 8), loliolide (9), and the known sesequiterpene (10). The structures of the isolated secondary metabolites were elucidated by 1H-NMR, 13C-NMR, COSY, HSQC, HMBC, NOESY, IR, UV, CD, MS, and optical rotation. The cytotoxicities against cancer cells, anti-inflammatory effects, and anti-HCMV (human cytomegalovirus) activities of these isolated metabolites were evaluated.