The aim of the research was to discuss the inhibitory effect of polyphenol from lotus seed red-skin on α-glucosidase activity. It was designed to measure the α-glucosidase activity in different conditions using spectrophotometry. With the inhibitory effect on α-glucosidase activity as the index, the inhibitory conditions were optimized by the L₉ (3⁴) orthogonal optimization method. The results revealed that the optimal inhibition rate was 67.99%±1.79% at pH 6.8,1.50g/L of polyphenol concentration and 20min of reaction time. In addition, polyphenol was an anti-competitive inhibition type of inhibitor on α-glucosidase, and its inhibition constant was 0.24g/L.