Ce³⁺，Cd²⁺ and Pb²⁺ could influence the activity of amylase from porcine pancreas and competitively replace Ca²⁺ from amylase. The results showed that the activity of amylase was enhanced under the treatment of Ce³⁺，Cd²⁺ and Pb²⁺ respectively at low concerntration, but inhibited at the high concerntration. Both replacement and inhibition showed that the action was in the order: Pb²⁺＞Cd²⁺＞Ce³⁺.