Abstract: Conventional refluxing extraction and ultrasound assisted extraction were adopted to extract tannins from leaf,bark and core of Eucalyptus Grandis x E.Urophylla. Moreover the antioxidant activity of tannins extracts also was studied. The yields of tannins from leaf,bark and core by conventional refluxing extraction were 4.19%,1.86% and 0.25% respectively,but that were 3.20%,2.25% and 0.19% respectively by ultrasound assisted extraction. The tannins extracts of Eucalyptus Grandis x E.Urophylla different parts had a strong scavenging activity to DPPH·,·OH free radical and H2O2. The scavenging activity of tannins extracts from leaf,bark and core on DPPH· were the equivalent to VCof 91.08%,93.20% and 79.40%,respectively. And the scavenging activity of 3 tannins extracts on ·OH reached 181%,125% and 132% of VC,on H2O2 equal to83.60%,65.46% and 78.46% VC.