[Objective]The research aimed to screen α-glucosidase inhibitor from Polygonum cuspidatum Sieb.et Zucc.[Method] The ability of the extract from Polygonum cuspidatum Sieb.et Zucc.to inhibit α-glucosidase was studied and the crude inhibitor was screened.[Result]The results showed that the inhibition rate of 50 mg/ml extract to α-glucosidase was 68.5%,its IC50 was about 37 mg/ml.The Polygonum cuspidatum Sieb.et Zucc.extract was noncompetitive inhibitior of α-glucosidase,and the Ki was 33 mg/L.The crude inhibit...