To investigate monoterpenes and sesquiterpenes of the stems and leaves of Clausena excavata, an AcOEt fraction of the methanol extract was subjected on column chromatographies including silica gel and RP-18, as well as preparative HPLC. The structures of compounds isolated were identified on the basis of spectroscopic data as excamonoterpene (1), (6R, 9S)-9, 10-dihydroxy-4-megastigmen-3-one (2), (3R, 6R, 7E) -3-hydroxy-4, 7-megastigmadien-9-one (3), (3S) -3-hydroxy-7, 8-dihydro-beta-ionone (4), (3S, 5R, 6S) -3-hydroxy-5,6-epoxy-beta-ionone (5), (6R, 9R) -9-hydroxy-4-megastigmen-3-one (6), (3S, SR) -dihydroxy-6, 7-megstigmadien-9-one(7), (-)-loliolide(8), caryolane-1, 9alpha-diol(9) and 2, 6-dihydroxyhumula-3 (12), 7 (13), 9(E)-triene (10), were isolated from the stems and leaves of C. excavata. Compound 1 is a new monoterpene, named as excamonoterpene. Compounds 2-10 were isolated from this plant for the first time.