Two dihydroxypyranone compounds were synthesized by acetylation, palladium hydrogenation, carbonyl α-acetoxylation and deacetylation from maltol or ethyl maltol. The structure of each reaction products were characterized by 1H NMR, 13C NMR and high-resolution mass spectrometry, the synthesis process was optimized, and the antioxidant activity of the compounds were tested by quenching free radical reaction system. The results showed that the scavenging rates of dihydroxypyranone on ABTS+?, DPPH? and galvinoxyl? were 88.9%, 83.8% and 68.4% respectively, which were significantly higher than those of vitamin E and butylated hydroxytoluene. The structure-activity relationship study shows that the introduction of hydroxyl groups into the structure of pyranone or the enhancement of the electron donating ability of side chain substituents can improve the free radical scavenging ability of compounds, which provides a reference for the synthesis and development of new antioxidants.