Cyclocarya paliurus (Batal.) Iljinsk (C. paliurus) commonly known as ‘sweet tea tree’ is a medicinal herb, which has been widely used in China as drug formulation in traditional Chinese medicine for the treatment of diabetes mellitus. The aim of this study was to investigate the antioxidant activity of the ethanol extract from leaves of C. paliurus and screen the active fractions separated from the ethanol extract. Five antioxidant methods were established including total reducing power, 2, 2-diphenyl-1- picrylhydrazyl, superoxide anion and hydroxyl radical scavenging activity assay and the inhibitory effect on H2O2 induced lipid peroxidation. The results showed that the ethanol extract from leaves of C. paliurus and the four different polar fractions exhibited antioxidant activities at different magnitudes of potency. Among these extracts, the ethyl acetate fraction showed the best antioxidant activity, which was much better than the crude ethanol extract. This research demonstrates that the ethyl acetate fraction from ethanol extract of C. paliurus might be valuable antioxidant natural source and applicable in both medicine and food industry.