PURPOSE: The purpose of this study was to compare the efficacy of focused ultrasound circumferential pulmonary vein ablation (CPVa) and BOX ablation (BOXa) in an acute atrial fibrillation (AF) model. METHODS: Twenty mongrel dogs were divided into either CPVa or BOXa groups. CPV or BOX focused ultrasonic ablation was conducted in each group after successful establishment of the AF model. Before-and-after ablation left atrial effective refractory period (LAERP), AF inducibility, and induced AF lasting time were measured in both groups. RESULTS: The LAERP after AF model establishment was significantly shorter than that before establishment (102 ± 10 vs. 140 ± 10 ms, p < 0.01, in the CPVa group; 105 ± 8 vs. 139 ± 11 ms, p < 0.01, in the BOXa group). The AF inducibility after ablation was significantly lower than that before ablation in the two groups (98% vs. 28%, p < 0.01, in the CPVa group; 97% vs.14%, p < 0.01, in the BOXa group), and the induced AF lasting time after ablation was significantly shorter than that before ablation in both groups (233 ± 40 vs. 70 ± 29 s, p < 0.01, in the CPVa group; 240 ± 41 vs. 34 ± 22 s, p < 0.01, in the BOXa group). On intergroup comparison, AF inducibility and induced AF lasting time after ablation were significantly lower/shorter in the BOXa group than those in the CPVa group (14% vs. 28%, p = 0.021; 34 ± 22 vs. 70 ± 29 s, p = 0.048, respectively). CONCLUSIONS: In the experimental AF model, the epicardial focused ultrasound BOX ablation may be more effective to prevent the recurrence of AF compared with the CPV approach.