To select Chinese medicine Eriobotrya japonica （Thunb.） Lindl. leaves with high hypoglycemic activity， contents of total ashes， extracts and triterpenoid acid components in crude and processed products of mature leaves and fallen leaves of E. japonica from Xishan Island in Suzhou of Jiangsu in November were compared， and their ability to inhibit α-glucosidase activity was also compared. The results show that contents of total ashes and extracts in different types of E. japonica leaves are in accord with related criteria. Contents of each triterpenoid acid component in fallen leaves are significantly higher than those in mature leaves in general， and total contents of triterpenoid acid components in crude and processed products of mature leaves， and crude and processed products of fallen leaves are 1.671 0％， 1.690 0％， 3.774 1％， and 2.717 5％， respectively. α-glucosidase inhibitory activity of different types of E. japonica leaves is significantly higher than that of acarbose， in which， half-inhibitory concentration （IC50） of crude product of fallen leaves is the lowest with only 64.170 μg·mL^-1. In conclusion， fallen leaves are the optimum choice for taking E. japonica leaves as hypoglycemic Chinese medicine.