A new phenylpropanoid derivative (1), along with five phenylpropanoids (2-6), two monoepoxy lignans (8-9), one bisepoxy lignan (10), two cyclolignans (11-12), six neolignans (7, 13-17), two mixed lignan-neolignans (18-19), two lignan glycosides (20-21), and four flavonolignans (22-25), were isolated from the stems and twigs of Euonymus acanthocarpus. Compounds 2-3, 6-8, 12, and 14-25 were obtained from Celastraceae family for the first time, and compounds 5 and 9 were isolated from Euonymus genus for the first time. All the compounds were tested for cytotoxicity against SK-OV-3 and MCG-803 human tumor cell lines. Compounds 3, 10, 12, and 18 showed weak cytotoxicity against SK-OV-3 cell line, and compounds 3-4, 10-13, and 19 showed weak cytotoxicity against MCG-803 cell line.