To study the chemical constituents of the petroleum ether extract from Alocasia cucullata (Lour.) Schott,a plant species belonging to the Araceae family.Silica gel,Sephadex LH-20 and other chromatographic methods were used for separation and purification,and spectroscopic techniques were employed for structural identification.The in vitro assessment of all isolated compounds was conducted using the CCK-8 assay on human breast cancer cell lines MDA-MB-231 and MCF-7,as well as mouse breast cancer cells 4T1.Fifteen compounds were isolated from the petroleum ether fraction of the rhizome of A. cucullata and their structures were identified as p-hydroxybenzaldehyde (1),benzoic acid (2),ethyl vanillate (3),ethyl gallate (4),7-hydroxycoumarin (5),myristate (6),squalene (7),oleanolic acid (8),ursolic acid (9),sclareol (10),sclareolide (11),protocatechualdehyde (12),protocatechuic acid (13),octacosanol (14) and gallic acid (15).Compounds 2-15 were first isolated from genus Alocasia.All the compounds were first isolated from A. cucullata.The cytotoxicity study of breast cancer cell showed that compounds 4,8 and 9 had inhibitory effect on all three kinds of breast cancer cell lines.