Abstract: Atrial fibrillation (AF) is the most common cardiac arrhythmia. Pulmonary vein is an important origin site of electrophysiological activity of atrial potential, which can lead to AF. The mapping of atrial arrhythmia origin from pulmonary vein is to determine the key to success of the AF catheter ablation procedure. Atrial arrhythmia related to electrical activity of thoracic vein can be treated by circumferential pulmonary vein ablation. The isolation of electric structure between the thoracic vein and atria can prevent or halt atrial arrhythmia and then can maintain sinus rhythm. By analyzing the morphological character of atrial arrhythmia P wave, the target of atrial arrhythmia originating from pulmonary veins can be roughly located.