Abstract： Objective To investigate the anatomic, electrophysiological and therapeutic characteristics of catheter ablation of atrial fibrillation (AF) with a common ostium of inferior pulmonary veins (PVs) under the guid-ance of image integration system. Methods A total of 1381 patients with drug-refractory AF received magnetic reso-nance angiography (MRA) or multidetector computed tomography (MDCT) scan and LA and PVs reconstruction by image integration system (CartoMergeTM software)before ablation. Electrophysiological mapping was used to detect the focal triggers in paroxymal AF. Basic catheter ablation strategy was circumferential PV isolation with "triple circles" under the guidance of image integration system: two circles surrounding two superior PVs and the third surrounding the common ostium. Results LA and PVs reconstruction by image integration system showed a common pulmonary venous ostium of the right and left inferior PVs before ablation in 12 patients (0.8%). This anomaly could be classified into two types: typeIwithout a short common mink of inferior PVs and typeⅡ with a short common trunk. Most of paroxymal AF was revealed of focal triggers in the common cerium. The success rate of that strategy was 83%. Conclusion Common nstium of inferior PVs could be classified into two types according to presence of a short couunon trunk or not. The common ostium is an important triggering focus in paroxymal AF. Catheter ablation strategy of circumferential PV isolation with "triple circles" under the guidance of image integration system in patients with that anomaly may be a good choice.