Using acarbose as positive control and half-inhibitory concentration value (IC₅₀) as evaluation index,and inhibitory effects of different polarity fractions of the ethanol extracts from Tadehagi triquetrum on the activities of α-glucosidase (from yeast and small intestine in mice) were evaluated with in vitro inhibition model.The enzymatic dynamics and Lineweaver-Burk methods were used to analyze the inhibitory type of the best medicinal part on the activities of α-glucosidase,which will provide a reference evidence for the application of effective polarity fraction from T. triquetrum in medical,food,and chemical fields.The results indicated that inhibitory activity of different polarity fractions of the ethanol extracts from T. triquetrum on the activities of α-glucosidase (from yeast and small intestine in mice) were n-butanol fraction>water fraction>ethylacetate fraction>petroleum ether fraction.n-Butanol fraction of T. triquetrum had the stronger inhibition activity against α-glucosidase (IC₅₀ to α-glucosidase from yeast and α-glucosidase from small intestine in mice were 13.08±1.23 and 221.21±3.75 μg/mL,respectively) than other fractions and reference substance acarbose (P<0.05).Kinetic analysis showed that the inhibitory mechanism of n-butanol fraction on α-glucosidase was competitive inhibition.The n-butanol fraction from the T. triquetrum exhibited the highest α-glucosidase inhibitory activities,indicated that it was a good source of nature could be used as the main active fractions to excavate active substances for inhibition activity on α-glucosidase.