Abstract: The tannins content in the bark of 4 ages Eucalyptus robusta Smith and E.urophylla in the Guangxi Gaofeng Wood Farm were determined. The vegetable tannin extracts were prepared. It was found that the tannins of the E.robusta Smith and E.urophylla belong to condensed tannins. The tannin content of bark are 7.6% and 7.8%, respectively, the purity are 67.9% and 70.3%;the tannin content of the E.robusta Smith bark extract is 65.4%, and E.urophylla bark extract is 63.3%.The Eucalyptus bark can been used as the new raw material of tannin extract, its tannin extract is worth of promoting and using.

Key words: Eucalyptus bark, tannin, raw material of tannin extract