Abstract: Increase of P wave dispersion (PWD) is an index of atrial fibrillation but the mechanism of PWD increase is not clear. A large number of clinical studies have shown that patients with increased PWD shared some pathophysiological pathways including abnormality of flow dynamics, myocardial metabolic abnormality, inflammatory reaction, oxidative stress, and increase of autonomic nervous tension. Damage of cardiovascular functions thus caused is irreversible, occult, progressive and slow. As the change of PWD is associated with cardiovascular dysfunction, this paper aims at discussing the value of diagnosis and treatment of PWD changes in cardiovascular diseases.