Various ion currents on the myocardial cell membrane take part in cardiac electric activity under both physiological and pathological conditions. Cardiac sodium current (INa) is involved in the depolarization and repolarization of cardiomyocyte action potential (AP), and exerts an important effect on the conduction of AP. So, it is of great importance to explore the interactions, effects, and especially, clinical significance of INa with other ion channel currents. This study reviewed the interaction of INa with other cardiac currents, and elucidated the mechanism of cardiac arrhythmias from the perspective of ion flow interaction.