To study the hypoglycemic effect and pancreatic pathological changes of Yi'aoyuan capsule on mice. Methods:The model of type II diabetes mouse were randomly divided into the model control group, the positive control group, the low, medium and high dose of Yi'aoyuan capsule group and the normal group with common feed, with 10 mice in each group. The positive control group was given 400 mg/kg metformin hydrochloride by gavage. Mice of Yiaoyuan capsule group were administrated by intragastrical gavage with 3 dosage of Yi'aoyuan capsule (3.0, 6.0, 12.0 g/kg). The model control group and the normal group received the same volume of distilled water intragastrically. The drugs were administrated once a day for 40 days. The weight and blood-sugar level of mice were calculated weekly. Islet tissue pathology and electron microscopy islet cell were observed after the last administration using two mice obtained from each group, of which blood-sugar level were close to the average. Results:Compared with the model control group, the weight of the first week and third week of the low dose group of Yi'aoyuan capsule increased (34.15±4.21 g vs 38.81±4.56 g, 34.70±3.78 g vs 39.81±5.63 g); blood-sugar level of the first, third and fourth week decreased (16.47±5.43 mol/L vs 24.59±2.70 mol/L, 15.60±5.73 mol/L vs 22.42±4.96 mol/L, 14.37±5.25 mol/L vs 23.38±5.18 mol/L); The damaged islet cells of mice could be improved and the islet β cells could be repaired by Yi/aoyuan capsule. Conlusion:Yi/aoyuan capsule has a significant hypoglycemic activity and it also has a function to repair islet β cells.