Objective: To study the chemical constituents from the leaves and twigs of Callicarpa cathayana. Methods: The chemical constituents were isolated and purified by column chromatography on silica gel, MCI gel CHP 20P/P120, Sephadex LH-20, and HPLC. The structures of the compounds were determined by HR-ESI-MS, 1D and 2D NMR data. Results: A total of 24 compounds were isolated from the 85% methanol extract of leaves and twigs of C. cathayana. They were identified as cathayanalactone G (1), a new diterpene, and 23 known compounds as patagonic acid (2), (-)-16-hydroxycledroda-3,13-dien-16,15-olide-18-oic acid (3), 15-methoxypatagonic acid (4), oleanolic acid (5), ursolic acid (6), siaresinolic acid (7), pomolic acid (8), α-amyrin (9), tormentic acid (10), lupeol (11), 5,7-dihydroxy-3,4′-dimethoxyflavone (12), 5,4′-dihydroxy-3,7,3′-dimethoxyfla-vone (13), 5-hydroxy-3,6,7,4′- tetramethoxyflavone (14), salvigenin (15), kaemferol (16), astragalin (17), pinoresinol 4-O-β-D-glucopyranoside (18), paulownin (19), β-sitosterol (20), β-sitosterol β-D-glucopyranoside (21), 5-hydroxy-coumarin (22), isocopoletin (23), and 4-hydroxycinnamic acid (24). Conclusion: Compound 1 is a new labdane diterpene. Compounds 10, 13, 16 and 17 are isolated from the genus Callicarpa for the first time. Compounds 7, 8, 9, 12, 14, 23 and 24 are reported from C. cathayana for the first time.