Abstract: Objective: To explore the clinical efficacy of radiofrequency catheter ablation in patients with pre-excitation syndrome and paroxysmal atrial fibrillation, and to provide reference for clinical treatment.Method: Thirteen patients with preexcitation syndrome and paroxysmal atrial fibrillation who delivered to our hospital from January 2013 to December 2017 were selected as the study group. The clinical efficacy of radiofrequency catheter ablation was evaluated by non-control open-ended study. ECG examination and recurrence were performed before, after the intervention, and six-month follow-up. The difference of the diameter of each chamber between the 20 healthy subjects and the study group was compared.Result: There was no significant difference in the diameter of left atrium and right atrium between two groups (P>0.05). In study group, after radiofrequency ablation, the function of anterograde/reverse passage was blocked, the effective refractory period of atrium, the maximum value of P wave, the minimum value of P wave, the dispersion of P wave, the P-R interval, QRS and QTC indexes were significantly improved (P<0.05). The recurrence rate of AF was 15.38% after 6 months of follow-up. The indexes of left atrial diameter, age, P-R, QRS of recurrent patients were worse than those of non-recurrent patients (P< 0.05).Conclusion: radiofrequency catheter ablation is safe and effective in the treatment of preexcitation syndrome with paroxysmal atrial fibrillation. The electrophysiological indexes of ECG are significantly improved. The electrical remodeling of accessory pathway and atrium may play a role in triggering and maintaining the patients with pre-excitation syndrome with paroxysmal atrial fibrillation. The recurrence of atrial fibrillation can be predicted by left atrial diameter, age, P-R interval, and QRS time limit.