Abstract: Experiments were conducted in 2016 on effect of different concentration (20, 40, 60 and 80 mg·mL-1) of aqueous extract from leaves of Eucalyptus urophylla with water as control on the growth and SOD, POD and CAT content in Ardisia gigantifolia seedlings. The results showed that the treatment of 40, 60 and 80 mg·mL-1 of aqueous extract could evidently decreased height growth of A. gigantifolia seedlings (P<0.05). No any treatment had evident effect on root length, dry weight of underground and biomass (P<0.01), but there was a significant difference of root length, dry weight of underground and biomass between seedlings treated by high concentration and that by the left concentrations (P<0.01). Compared with the control, aqueous extract significantly increased the activity of SOD, POD and CAT (P<0.05). Allelopathic index of height, ground diameter, root length and biomass of A. gigantifolia seedlings was less than 0, and the absolute value of allelopathic index topped under the treatment of 80 mg·mL-1. Integrated analysis indicated that E. urophylla could not be planted with A. gigantifolia because their strong negative allilopathic effect.