3,5,7,3',4',5'-Hexaacetyldihydromyricetin(1), 3,3',4',5'-tetraacetyldihydromyricetin (2), 3,7,3',4',5'- pentaacetyldihydromyricetin (3), 3-acetyldihydromyricetin (4) and acetone adduct of dihydromyricetin (5) were synthesized from dihydromyricetin (6) with different acylating reagents under different catalytic conditions. Their structures were confirmed through MS, ^1H NMR and ^13C NMR. Their antioxidant activities were evaluated by the clearance effect to hydroxyl radical and superoxide anion. The results showed that the a...