Objective To observe the changes and significance of the protein expression levels of nuclear factor-κB p65 (NF-κB p65), transforming long factor-β1 (TGF-β1) and apoptosis-related factors Bcl-2 and Bax in myocardial tissue of Bama miniature pig model of diabetic cardiomyopathy (DCM). Methods Ten healthy male Guangxi Bama miniature pigs, aged 4 to 5 months old, were selected and divided into control group and model group according to the random number table method, with 5 pigs in each group. After 12 hours of fasting in the two groups, the DCM model was replicated by intravenous injection of streptozotocin (STZ) 150 mg/kg; for the Bama miniature pigs in the control group, citric acid-sodium citrate buffer 150 mg/kg was injected intravenously. After 10 months of modeling, the basic conditions of the two groups of animals were observed and their fasting blood glucose (FPG) levels were detected. The protein expression levels of NF-κB p65, TGF-β1, Bcl-2 and Bax in myocardial tissue of two groups were detected by Western Blot and the pathological changes of myocardial tissue were observed under electron microscope. Results In the model group, 4 models were successfully established, and 1 died. The model pigs had symptoms such as polydipsia, polyphagia, polyuria and decreased body weight. The FPG level in the model group was significantly higher than that in the control group (mmol/L: 25.53±3.75 vs. 4.68±0.77, P < 0.01). Compared with the control group, the protein expression levels of NF-κB p65, Bax and TGF-β1 in the myocardial tissue of model group were significantly increased (NF-κB p65/GAPDH: 0.46±0.05 vs. 0.38±0.02, Bax/GAPDH: 0.46±0.01 vs. 0.35±0.01, TGF-β1/GAPDH: 0.39±0.01 vs. 0.33±0.01, all P < 0.05) and the expression level of Bcl-2 protein was significantly decreased (Bcl-2/GAPDH: 0.33±0.01 vs. 0.42±0.01, P < 0.01). Electron microscopy results showed that the myofibrils of myocardial tissue in the DCM model group were disordered, and the number of mitochondria in the gap was significantly reduced. A large number of mitochondria with vacuolar degeneration were observed. Conclusions The DCM model of Bama miniature pigs can be successfully replicated after 10 months of high-dose STZ disposable ear vein injection. The DCM model miniature pigs have obvious glucose metabolism disorder, and their myocardial tissue has inflammatory reaction, cardiomyocyte apoptosis and fibrosis.