Abstract: In this study， 7yearold Huangguogan trees were used as the materials， 4 different boron treatments were set， to study the effect of boron on physiological and antioxidant enzymes activities in Huangguogan roots and leaves. The results showed that the insoluble boron content was increased by 1-7 folds in Huangguogan leaves compared with the control. Insoluble boron was the main form in the roots and leaves. The contents of proline and boron were significantly increased by boron treatments in Huangguogan roots and leaves. There was no significant difference in malondialdehyde （MDA） content in leaves. The lower and higher concentrations of boron could significantly reduce the chlorophyll content， decrease CAT， POD and SOD activities， and increase cell membrane permeability of the leaves in the late fructescence. When boron content was higher， the content of proline was accumulated， which could activate the oxidative stress reaction， and result in reduction of boron toxicity in Huangguogan roots and leaves.

Key words: boron, Huangguogan, proline, malondialdehyde, antioxidant enzymes