Objective To investigate the protective effect of Jinlida granules on islet β cells in diabetes mellitus rats. Methods Diabetic models were induced by high-fat diet and intraperitoneal injection of streptozotocin (STZ ) in SD rats. The study was divided into model group, Jinlida granule group (0.75, 1.5, 3.0 g/kg), α-lipoic acid group, insulin group, and metformin group. Each group was given corresponding drugs, with insulin given by subcutaneous injection and other drugs given by intragastric administration. The body weight, fasting blood glucose(FBG), fasting insulin (FINS), glycosylated hemoglobin (HbA1c), the activities of superoxide dismutase (SOD) and glutathione(GSH), and the contents of malondialdehyde(MDA), IL-1β and TNF-α were examined 2 months later. The pancreatic tissues were immunostained for insulin. Results Compared with the model group, the levels of FBG and HbA1c were decreased in other groups(P<0.05, P<0.01). The activities of SOD and GSH were significantly increased (P<0.01) and the levels of MDA, IL-1β and TNF-α were significantly decreased (P<0.01) in high-dose (3.0 g/kg) Jinlida granule group, with increased islet area as shown by pathological staining. Conclusion Jinlida granule has protective effect against STZ-induced islet β cell injury in diabetic rats.