Abstract: AIM: To study the chemical constituents from the stems of Aquilaria sinensis (Lour.) Gilg. METHODS: Chromatographic separations of silica gel, Sephadex LH-20 and prep-HPLC were used. All the structures were elucidated on the basis of chemical and spectroscopic analysis. RESULTS: Twelve flavonoids were isolated and their structures were identified as aquilarinoside A1 (1), lethedioside A (2), 7, 4'-dimethylapigenin-5-O-xylosylglucoside (3), lethedoside A (4), 7-hydroxyl-4'-methyl-5-O- glucosideflavonoid (5), 7, 3'-dimethyl-4'-hydroxyl-5-O-glucosideflavonoide (6), 7, 4'-dimethyl-5-O-glucosideflavonoide (7), 5-hydroxyl-7, 4'-dimethoxyflavone (8), luteolin-7, 3', 4'-trimethyl (9), hydroxylgenkwanin (10), 5, 7-dihydroxyl-4'-methoxyflavone (11), and formononetin (12). CONCLUSION: Compound 1 is a new flavone glycoside, and compounds 2, 4-7 were isolated from genus Aquilaria sinensis for the first time. 5-O-glycosylflavones 1-7 showed inhibitory activity for nitric oxide (NO) production by activated RAW 264.7 cells.