Effect of external copper on enzyme activity in a soil and apple tree system was studied by us-ing cinnamon soil and Fuji apple young tree.The results showed that perioxidase,PPO and ascorbic acid oxidase act ivity in the leaves and perioxidase activity in the roots were reinforced at low external copper levels and reduced at high.Adding Ca of Fe at high copper levels could mitigate copper toxicity in some degree.A significant curuilinear correlation was observed between soil peri-oxidase activity and the external copper concentration(y=x/(-11.26+0.75x),r=0.9955^**).Soil sucrase activity was logistically correlated with the external copper level(y=2.95/(1+0.57exp(-5.02×10^-5x)),r=-0.9820^**).Urease was very sensitive to copper and it lost activity at levels> Cu100.