Aim To study the effects of first using amiodarone and then using ibutilide on efficacy and transmural dispersion of repolarization in cardioversion of new(7 d～90 d) persistent atrial fibrillation(PAF).Methods 76 patients of new PAF were randomly divided into two groups:ibutilide group (38 cases) and sequential group (38 cases). Patients(38 cases) in the ibutilide group were treated with ibutilide intravenous injection, initial dose 1 mg(or 0.01 mg/kg), slow injection after dilution; amiodarone group(50 cases) were treated with amiodarone intravenous injection on conversion, initial dose 150 mg, diluted uniform injection for 10 min. If it failed, the same dose and method were used for the second time at intervals of 10 min; Patients(38 cases) in the sequential group were first diluted with amiodarone at 150 mg and then injected with it at a constant rate for 10 min. If it failed, 1 mg (or 0.01 mg/kg) of ibutilide was used to dilute the solution and then inject at a constant rate for 10 min. The success rate of atrial fibrillation recovery within 24 h after second administration, the incidence of ventricular arrhythmia were compared between two groups, changes in the ratios of QT interval and Tpeak-end/QT interval ratio (30 min, 1 h, 3 h, 4 h) were detected. Results After the first injection, the success rate of atrial fibrillation was higher than that of amiodarone(P＜0.05); Total reinjection, comparison of the success rate of PAF reversion between the two groups (P＞0.05), showed no significant difference. In patients with successful outcome, the dosages of ibutilide individuals in the sequential group were significantly lower than that in the ibutilide group(P＜0.01); Tpeak-end/QT in the ibutilide group was higher than that in the sequential group immediately after medication and 30 min after medication(P＜0.01); The tpeak-end /QT of the ibutilide group was significantly increased immediately after the end of the treatment(P＜0.05), after 1 h of administration, the drug returned to the level before administration(P＞0.05); Comparison of each time point after administration and before administration showed that there was no statistically significant difference of the Tpeak-end/QT in the sequential group(P＞0.05). Conclusion The atrial fibrillation conversion rate of ibutilide was higher than that of amiodarone, however, the transmural dispersion of repolarization(Tpeak-end/QT) increased after ibutilide alone; for first using amiodarone and then using ibutilide, compared to the single usage of ibutilide for twice, the success rate of atrial fibrillation is comparable, the transmural dispersion of repolarization(Tpeak-end/QT)do not increase, there is a tendency to reduce the incidence of ventricular arrhythmia.