In vitro inhibitory effects of six triterpene acids （including euscaphic acid， tormentic acid， corosolic acid， maslinic acid， oleanolic acid， and ursolic acid） from leaf of Eriobotrya japonica （Thunb.） Lindl. on α-glucosidase activity and production of nonenzymatic glycosylation products Amadori and AGEs were studied. The results show that the six triterpene acids have strong inhibitory effects on α-glucosidase activity， with semi-inhibitory concentration （IC₅₀） of 0.76-35.45 μg·mL^-1， in which， ursolic acid has the strongest inhibitory effect. The six triterpene acids show inhibitory effects on Amadori formation， and the inhibitory effects decrease significantly with the decrease of mass concentration， in which， 50 μg·mL^-1 euscaphic acid has the strongest inhibitory effect， with inhibition rate of 83.63%； however， the six triterpene acids have no evident inhibitory effect on AGEs formation， and the inhibition rate of 50 μg·mL^-1 euscaphic acid has the strongest inhibitory effect， but the inhibition rate is only 18.71%. In conclusion， triterpene acids from leaf of E. japonica have potential therapeutic effects on diabetes and its complications.