Objective:To assess the feasibility and efficacy of radiofrequency catheter ablation (RFCA) of arrhythmias with low dose X-ray in children guided by three-dimensional mapping system.Methods:Fourteen children with tachyarrhythmia who were transferred to Tianjin Medical University General Hospital after being hospitalized in Tianjin Children′s Hospital and underwent RFCA from April 2017 to May 2018 were included.The results of intraoperative electrophysiological examination, intraoperative X-ray dosage,the immediate success rateand complications of RFCA,and the recurrence during the follow-up for at least 6 months were recorded.Results:Among the 14 children, 11 cases were diagnosed with supraventricular tachycardia.Five cases had atrioventricular reentrant tachycardia (AVRT) which included two cases with left accessory pathway and three cases with right accessory pathway, and four cases had atrioventricular nodular reentrant tachycardia (AVNRT), one case had atrial flutter (AFL), one case had both AFL and AVNRT. One case had focal atrial tachycardia, one case had ventricular tachycardia, and one case had premature ventricular contraction. Eleven cases underwent RFCA with zero radiation, and 3 cases underwent atrial septal puncture with low dose X-ray. The exposure amounts were 3.85, 3.23 and 4.67 mGy, respectively. No complications occurred except for one case with AVRT had atrioventricular block and recovered to normal in 25 days after operation.During the follow-up of 7 to 20 months, no arrhythmias had been found in 13 cases, and one case with AVRT and AFL recurred.Conclusion:Under the guidance of three-dimensional mapping system, RFCA of tachyarrhythmia with low dose X-ray in children is feasible.