Abstract: Three limonoids were isolated and purified from the 95%, 85% ethanol extracts of Melia azedarach using silica gel column chromatography, Sephadex LH-20 column chromatography, MCI column chromatography, and preparative RP-HPLC. Their structures were determined based on physicochemical properties and spectral data, and they were identified as 29-O-ethyl neoazedarachin D (1), 29-O-meliarachin G (2), toosendanin (3). Compound 1 is a new limonoid, while compound 2 is a new natural product isolated from plants for the first time. The in vitro anti-hepatocarcinoma activities of compounds 1-3 were evaluated by MTT assay. The results showed that compounds 1-3 exhibited different degrees of inhibitory effects on both HepG-2 and Hep3B cell lines, and the inhibitory effect of compound 3 on HepG-2 cells was comparable to that of the positive drug cisplatin. In addition, compounds 1-3 exhibited IC₅₀ values of 38.67 ± 1.336, 28.21 ± 1.028 and 8.21 ± 1.231 μg·mL^-1 against HepG-2 cells, and 47.36 ± 1.008, 35.69 ± 1.217 and 15.10 ± 1.017 μg·mL^-1 against Hep3B cells, respectively.