The objective of this study was to clarify the relationship between angiotensin II and the pathogenesis of diabetic cardiomyopathy by observing the effects of related drugs on diabetic cardiomyopathy in rats. Captopril and Valsartan, an automatic biochemical analyzer, and radioimmunoassay technology were used to an experimental rat model of diabetic cardiomyopathy to dynamically measure the levels of creatine kinase-MB, lactate dehydrogenase-1 in the serum, and angiotensin I and II in the plasma, and to observe changes in the myocardial ultrastructure. The content of angiotensin I and II was increased and the renin–angiotensin system was in a hyperfunctional state in experimental rats with myocardial damage. Angiotensin-converting enzyme inhibitors and angiotensin II receptor 1 antagonists improved the myocardial structure and cardiac function. It is concluded that hyperfunction of the renin–angiotensin system is involved in the pathogenesis of diabetic cardiomyopathy,with an increase in angiotensin being a key factor. Preventing the increase in angiotensin II or the action of angiotensin II on its receptor can prevent the occurrence and development of diabetic cardiomyopathy.