Abstract: Extracted tannin from Eucalyptus citriodora fruits by using ultrasonic-assisted extraction, and compare the yield of tannin from two different methods of solvent extraction and ultrasonic-assisted extraction. The crude extract of tannin was purified by solvent process, macroporous resin adsorption and both methods combined. And the total antioxidant activity, the ability of removal DPPH·and·OH radical of different samples were examined. The results showed that, tannin in crude extract was 9.43%.The optimum adsorption and separation for the crude extract on X-5 macroporous resin were as follows: the feed concentration of 0.6 mg/mL with flow rate of 1.0 m L/min, the desorption solvent was 60% ethanol with flow rate of 1.5 mL/min.The purified of the ethyl acetate extract, macroporous resin purification substance, ethyl acetate residue purified by macroporous resin, ethyl acetate extracts purified by macroporous resin were 32.05%, 58.52%, 83.07% and 85.31%. Respectively, the maximum total antioxidant activity was macroporous resin purification substance, 135.47% for tannins.The maximum scavenging rate of different samples referred above for DPPH· were 66.09%, 52.48%, 92.18%, 44.10% and 44.09%, when the mass concentration was 0.01 mg/mL.But the maximum scavenging rate of different samples referred above for ·OH were 67.92%, 58.17%, 68.12%, 61.68% and 74.61%, with the concentration of 1.0 mg/mL.