Abstract: Objective to explore the inhibitory effect and type of sweet corncob polysaccharide on α-amylase, and on this basis, to investigate its inhibitory effect on mouse α-amylase. SCP50, a component of sweet corncob polysaccharide, was isolated and purified by hot water extraction and column chromatography. The inhibitory effect of SCP50 on α-amylase from rat small intestine was investigated by enzyme inhibition kinetics in vitro and animal experiments. The results showed that the inhibition of SCP50 on α-amylase was reversible competitive inhibition, and the competition mode was high activity competition, which could rapidly reduce the reaction speed of α-amylase, K_m was 0.669, V_max was 0.1437 mol/L·min^-1. In the rat intestinal enzyme inhibition test, SCP50 showed inhibitory effect on α-amylase isolated from small intestine of normal rats, IC₅₀ 263 mg/mL in a dose-dependent manner. In conclusion, SCP50, a component of sweet corncob polysaccharide, may have potential antidiabetic effect by inhibiting α-amylase activity and delaying glucose absorption in small intestine.