Twelve flavonoids were isolated from Allium macrostemon leaves. Five compounds were identified as kaempferol 3,7-di-O-glucoside (1), kaempferol 3,4'-di-O-glucoside (2), quercetin 3-O-glucoside (3), kaempferol 3-0-glucoside (4) and isorhamnetin 3-O-glucoside (5) by UV spectra, LC-MS, acid hydrolysis