This study analyzed complex fractionated atrial electrogram (CFAE) and CFAE ablation for atrial fibrillation patient. We modeled atrial fibrillation by a 3D virtual heart. For this purpose, measurement techniques of cardiac ablation using catheter was numerically implemented by a simulation method, and FIR filtering was used to analyze electric signal pattern measured. Through these methods, CFAE values was calculated in the 3D mapping at virtual heart, and we found ablation target of atrial fibrillation patient. This study also simulated CFAE and CFAE-based ablation for 20 patients and the computed results were compared with actual clinical data.