Objective: To investigate different extracts of Polygonum capitatum on inhibitory activity to α -glucosidase. Method: Different extracts were extracted by Soxhlet

and the inhibitory activity to α- glucosidase was screened by the 96-microplate-based method. Results: The results showed that P. capitatum had good inhibitory activity. The methanol extract had the highest inhibitory activity to α -glucosidase (IC50 1.68 μg·mL-1)

and then the ethyl acetate extract (IC50 7.27 μg·mL-1) and the petroleum ether extract (IC50 116.81 μg·mL-1)

three extracts of P. capitatum showed higher activity than Acarbose (IC50 1 081.27 μg·mL-1). And all of the extracts showed dose dependent for the inhibitory activity. Conclusion: The methanol extract of P. capitatum showed very significant inhibitory activity to α -glucosidase

and could be exploited the diabetes drugs as α- glucosidases inhibitors in future.