Abstract:To study the antioxidant activity of the different polarities of ethanol extract of fruit from Rose xanthina Lindl.in vitro.The antioxidant activity was measured with the methods of DPPH·scavenging，pyrogallol autoxidation and phenanthroline by using ascorbic acid as the positive control.Measured total flavonoids in the ethyl acetate with the methods of Sodium nitrite-aluminium nitrate chromogenic，phenolic compounds determine by Foline-reagent method.The results showed that the extracts had some certain.antioxidant activity，and exhibited a concentration-dependent radical scavenging activity in a certain concentration range.Different ploarities had different ability of scavenging free radical，in which the ethyl acetate fraction of the fruit had the most potent free radical scavenging activity on DPPH·，O2-·，·OH，with IC5018.52，737.00，605.51 μg/mL，respectively.Furthermore the ratio of the total flavoroids in the ethyl acetate fraction of the fruit was 15.50%and the phenolic compounds was 26.59%.The flavonoids and polyphenols of different polarity had the same effect on antioxidant（R2黄酮and R2多酚were between 0.98-0.37）.The ethyl acetate of the fruit is a potential natural antioxidant，It also can be further development and utilization of antioxidant functional food.