Abstract: The present study investigated the phenolics of hydrolysates of Osmanthus fragranslour by LC-MS/MS. The research results demonstrated that hydrolysates of Osmanthus fragranslour contained 36 varities of phenolics,including Caffeyolquinic acid,Caffeic acid 4-glucoside 4-O-p-coumaroylquinic acid,5-O-p-coumaroylquinic acid,Luteolin-7-O-6″-malonylglucoside,Acteoside,Isoacteoside etc. This study also evaluated the antioxidant activity of hydrolysates of Osmanthus fragranslour,Trolox and Rutin. It showed that scavenging activity of ABTS+and DPPH· free radical and reducing power of hydrolysates from Osmanthus fragranslour reached 90 % and were slightly lower than Trolox, but significantly higher than Rutin( p < 0. 05), when the concentration was greater than 0.8 mg/m L. The values of TEAC and ORAC of hydrolysates from Osmanthus fragranslour were 648.66 μmol Trolox/g and 813.53 μmol Trolox/g and significantly higher than Rutin(p<0.05). It was observed that the scavenging activity of ABTS+and DPPH· free radical and reducing power of hydrolysates from Osmanthus fragranslour had a significantly positive correlation with the contents of polyphenolics.