Amorpha fruticosa L. is a Chinese folk medicine and rich in polyphenols. Fifteen known compounds were isolated and identified from the leaves of A. fruticosa L. They are tephrosin (1), 6a,12a-dehydrodeguelin (2), vitexin (3), afrormosin-7-O-β-d-glucopyranoside (4), 2″-O-α-l-rhamnopyranosyl isovitexin (5), rutin (6), chrysoeriol (7), 7-O-methylluteolin (8), trans-p-coumaric acid (9), 2-benzyl-4,6-dihydroxybenzoic acid-4-O-β-d-glucopyranoside (10), formononetin (11), quercetin (12), apigenin (13), β-sitosterol (14), and β-daucosterol (15). Compounds 3, 4, 5, and 7–9 were isolated from A. fruticosa L. for the first time. Cytotoxicity of individual compounds 3–10 and 90% ethanol extract against human cancer cell lines HCT116 and HepG2 were reported. The results suggested that compounds 7 and 8, and the crude extract exhibited inhibitory effects on human cancer cell line HCT116, at concentrations of 100 μg/mL, 5 μg/mL, and 25 μg/mL at