Abstract: Objectives　To assess treatment outcomes and prognosis in infants with atrial flutter (AFL). Methods　Thirty-four (34) cases of infants with AFL in Hunan Children’s Hospital had been analyzed for clinical features, treatment outcomes and followup between March, 2009 and September, 2015. Based on ECG characteristics, the patients had been divided into simple and complex AFL groups.  Based on age, they had been divided into neonates and non-neonates group. The aim of this study is  to compare the clinical effects of drug treatment in different types of AFL. Results　With digitalis alone, the cardioversion rate was 37.5%，no significant difference was observed between simple and complex AFL groups (45.8% vs 12.5%, P=0.206). Combining with other drugs, the cardioversion rate was 54.5%, which showed significant difference between simple and complex AFL groups (76.9% vs 22.2%，P=0.036). The overall cardioversion rate was 70.6%, which showed significant difference between simple and complex AFL groups（87.5% vs 30%, P=0.003). There was no significant difference in pharmaceutical cardioversion rate between neonates and non-neonates group (85.7% vs 60.0%, P=0.216). Two cases with symptoms of heart failure used synchronized cardioversion. One patient restored to sinus rhythm, and another case was still recurrent of AFL after repeated electrical cardioversion, and eventually died of cardiogenic shock. After treatment, 9 patients were still with paroxysmal AFL and atrial tachycardia episodes, including 3 cases of simple type and 6 cases of complex type who were discharged with oral digoxin and propafenone treatment at home. 24 patients were followed up (3 months to 3 years and 4 months). 16 cases restored to sinus rhythm during hospitalization had no recurrence of AFL. Conclusions　The overall treatment effects of AFL in infants were good. In simple type of AFL, most of patients did not need long-term antiarrhythmic drug therapy and the prognosis was good. The prognosis of treatment with conventional drug was poor in complex AFL group, with a higher rate of recurrence of AFL.