Abstract: The inhibitory effect on porcine pancreaticα- amylase ( PPA) and its inhibitory mechanism of tannic acid ( TA) was investigated by UV-vis absorption and fluorescent spectrometry.As a non-competitive inhibitor, tannic acid showed significant inhibitory effect on PPA.The TA- PPA interaction was a spontaneous molecular process, and the TA- PPA binding site was closer to PPA trytophan residues. The UV absorbance at 270nm of PPA decreased and the absorption bands showed red-shift when it interacted with tannic acid.In addition, the intrinsic fluorescence of PPA could be significantly quenched by tannic acid.