Abstract: AIM: To investigate the chemical constituents from the stems of Celastrus orbiculatus Thunb.. METHODS: The chemical constituents were isolated and purified by silica gel, Sephadex LH-20 and ODS column chromatography. Their structures were elucidated on the basis of physical characteristics and spectral data. RESULTS: Eleven compounds were obtained and their structures were identified as 3-hydroxy-2-oxoolean-12-ene-22, 29-lactone (1), 2, 6-dimethoxybenzoquinone (2), 3-oxoolean-12-en-28-oic acid (3), 3-oxo-24-norolean-12-en-28-oic acid (4), 23-hydroxybetulonic acid (5), vanillic acid (6), 23-hydroxy-3-oxoolean-12-en-28-oic acid (7), syringic acid (8), oleanolic acid (9), -sitosterol (10), -daucosterol (11). CONCLUSION: Compound 1 is a new triterpene; compounds 2-5 and 7 were isolated from this genus for the first time and compounds 8 and 9 were firstly isolated from this plant.