There is a growing body of evidence that diabetes mellitus leads to a specific cardiomyopathy--diabetic cardiomyopathy (DCM), which is apart from vascular disease. Lethal cardiac arrhythmia is frequently found in DCM patients, which is associated with prolongation of the QT interval in electrocardiogram (ECG), causing increased mortality in the patients with diabetes mellitus. The change of ion channel is the basis for the prolonged cardiac action potential duration, mainly involving the change of calcium ions, potassium channels and sodium channels. In this paper we reviewed the recent progress in the changes of the ion channel in DCM patients.