Eucalyptus urophylla S.T.Blade MLA clone(MLA) was difficult to root species. E.urophylla S.T.Blade U 6 clone (U 6) and E.ABL 12 W 5 clone(W 5) were relatively easy to root species. The activity of peroxidase in every organ of MLA was higher than that in U 6 and W 5. The activity and isoenzymes of peroxidase were quite different both in different organs of the same species and in the same organs of different species. The peroxidase activity turned higher with the increasing maturity of the organs. The relationship between the peroxidase and rooting of Eucalyptus cuttings was discussed.