OBJECTIVE：To study the improvement effects of paeon iflorin（PF）on myocardial injury in type 2 diabetes mellitus（T2DM）model rats and its mechanism. METHODS ：The experiment was set up in the normal group ，model group ， positive control group （metformin 90 mg/kg），PF high-dose ，medium-dose and low-dose groups （90，60，30 mg/kg），with 8 rats in each group. Except for normal group ，other groups were given high-glucose and high-fat diet and intraperitoneal injection of streptozotocin （30 mg/kg） to induce T 2DM model. After modeling ， administration groups were given relevant medicine intragastrically，normal group and model group were given constant volume of normal saline intragastrically ，once a day ，for consecutive 4 weeks. The body weight ，fasting blood glucose and oral glucose tolerance were measured ；serum levels of glycosylated serum protein （GSP），total cholesterol （TC），triacylglycerol（TG），glutathione peroxidase （GSH-Px），superoxide dismutase（SOD），malondialdehyde（MDA），creatine kinase isoenzyme-MB （CK-MB） and troponin Ⅰ （cTn Ⅰ） were determined. The pathomorphological changes of myocardium were observed. The apoptosis index of rat cardiomyocytes was （ detected. The protein expression of B-cell lymphoma 2 （Bcl-2），Bcl-2 related X protein （Bax）and caspase- 3 in rat myocardium were detected by immunohistochemistry and Western blot. RE SULTS：Compared with normal group ，the body weight ，serum levels of GSH-Px and SOD ，protein expression of Bcl- 2 in myocardium were decreased significantly in model group（P＜0.01）；while fasting blood glucose ，area under blood glucose curve ，serum levels of biochemical indexes （GSP，TC， TG，MDA，CK-MB，cTnⅠ），cardiomyocyte apoptosis index ，protein expression of Bax and caspase- 3 in myocardium were increased significantly （P＜0.05 or P＜0.01）. The arrangement of myocardium was relatively irregular ，and some muscle fibers were broken. Compared with model group ，except for body weight ，serum levels of SOD and MDA ，the protein expression of Bax in myocardium in PF low-dose group ， above indexes of PF groups were reversed significantly （P＜0.05 or P＜0.01）. CONCLUSIONS：PF can regulate glycolipid metabolism ，enhance antioxidant ability ，inhibit cardiomyocyte apoptosis and improve myocardial injury in T 2DM model rats ；the mechanism may be associated with increasing the protein expression of Bcl- 2 and down-regulating the protein expression of Bax and caspase- 3 in myocardium.