To study the chemical constituents and antitumor activities in the stems and leaves of Macrosolen cochinchinensis (Lour.)Van Tiegh.Silica gel,macroporous resin,polyamide,MCI Gel,ODS,Sephadex LH-20 column chromatography and preparative high performance liquid chromatography were used to separate and purify ethanol extract from M. cochinchinensis,and modern spectroscopic techniques were used to identify 14 compounds,namely β-amyrin acetate (1),β-amyrin (2),lupeol (3),cycloeucalenol (4),campesterol (5),β-sitosterol (6),quercetin (7),quercitrin (8),gallic acid (9),rutin (10),ellagic acid (11),brevifolin (12),ellagic acid-4′-O-β-D-xylopyranoside-3,3′-dimethylether(13) and ellagic acid-4′-O-β-D-xylopyranoside-3,3′-dimethylether(14).All 14 compounds were isolated from  M. cochinchinensis for the first time.Taking A549 lung cancer cells as the research object,the inhibitory effect of compounds 1-14 on A549 lung cancer cells was determined by CCK-8 cell proliferation test kit.The effects of compound 14 on cell cycle distribution and apoptosis level change of A549 lung cancer cells were analyzed by flow cytometry.It was found that all compounds except compounds 1,2 and 4 had different inhibitory effects on A549 cells (IC₅₀=9.3-42.2 μg/mL),and compound 14 had the strongest effect,and its cell cycle was blocked in G1 phase,and the apoptosis rate increased significantly.Compound 3 and compounds 5-14 may be the main antitumor active components of  M. cochinchinensis.Compound 14 can inhibit the proliferation of A549 lung cancer cells,and its mechanism may be to induce apoptosis by blocking cell cycle.