Abstract: This chemical constituents of the aqueous extract of leaves of Cinnamomum longepaniculatum(Gamble) N. Chao ex H.W.Li were studied. Twenty-four compounds were isolated and purified by macroporous resin, PRP-512A resin, Sephadex LH-20, and etc. The structures of the compounds were identified by spectroscopic methods of UV, MS and NMR as 7-hydroxy-6-methoxy-coumarin(1), isofraxidin(2), dimethylmatairesinol(3), (+)-episesaminone(4), horsfieldin(5), (+)-epipinoresinol(6), (+)-pinoresinol(7), (+)-pinoresinol monomethyl ether(8), (+)-de-O-methylmagnolin(9), phillyrin(10),(2R, 3S)-4'-hydroxy-5, 7, 3'-trimethoxyflavan-3-ol(11), (2S, 3S)-4'-hydroxy-5, 7, 3'-trimethoxyflavan-3-ol(12), quercetin(13), loliolide(14), 2, 6-dimethoxy-1,4-benzoquinone(15), pyrocatechol(16), vanillic acid(17), 3-methoxy-4-hydroxyphenylethanol(18), dihydroconifery alcohol(19), 3, 5-dimethoxy-4-hedroxyphenylpropynol(20), 2-hydroxy-1-(4-hydroxy-3,5-dimethoxyphenyl) propan-1-one(21), methyl syringate(22), 1-(4-ethylphenyl)-1, 2-ethanediol(23), p-hydroxyacetophenone(24). Compounds 2, 5-6, 9-12, 14-16 and 18-24 were all isolated from Cinnamomum for the first time. The results of anti-hepatocellular-activity showed that compounds 2, 5 and 13 had moderate inhibitory activity effects on human liver cancer(HepG2) cells, with the half inhibitory concentrations(IC₅₀) values of 33.43, 107.40, and 71.43 μmol/L, respectively. Among them, the anti-hepatocellular-activity of compound 5 was reported for the first time. Compounds 2 and 13 belong to coumarins and flavonoids, which have good application prospects in the research of anti-tumor drugs.