Many patients develop atrial fibrillation after atrial septal occlusion, but the atrial septum is a mandatory route for catheter ablation of atrial fibrillation, so catheter ablation in these patients with atrial fibrillation was previously considered impossible. In recent years, by combining our proven techniques (inferior vena cava angiography, RAO septal puncture site localization technique, balloon dilation technique, etc.), we have been able to safely and successfully perform catheter ablation of atrial fibrillation after septal occlusion in these patients. There is not much information on the minimum time to perform catheter ablation after atrial septal occlusion, and we have completed such ablation for atrial septal occlusion for more than six months, so we limit ourselves to those who have had atrial septal occlusion for more than six months. The following is a case of catheter ablation for persistent atrial fibrillation after Amplatzer umbrella occlusion for congenital heart disease (Ma Changsheng et al.). The procedure was as follows: (1) Atrial septal puncture under the direction of inferior vena cava angiography, and the puncture sheath of the atrial septal sheath tube could not enter the left atrium. (2) 4.0 mm PTCA balloon dilation. (3) The atrial septal sheath tube enters the left atrium. (4) Atrial fibrillation ablation was performed with a CARTO saline-filled catheter and a 2C3L ablation strategy. Figure 2 CARTO diagram 2C3L ablation strategy