Abstract: Objective To discuss constituent ratio,concomitant disease and medication effects of malignant arrhythmias (MA) in children. Methods The clinical data of 70 children with MA diagnosed in our hospital from January,2012 to January,2016 were retrospectively analyzed.The constituent ratio of different types of arrhythmias and concomitant disease were described according to the diagnostic criteria of MA and concomitant diseases.The age distribution characteristics of different types of MA were investigated.According to the treatment outcome,the children were assigned into refractory arrhythmia group and non-refractory arrhythmia group.Fisher exact probability test was performed to analyze the distribution of different arrhythmias between the two groups. Results Among 70 children,there were 45 cases of male and 25 cases of female;there were 5 cases of atrial flutter,12 cases of atrial tachycardia,12 cases of atrioventricular heart-block,40 cases of supraventricular tachycardia,and 1 case of atrial tachycardia with auricular fibrillation.There were different types of arrhythmias at different ages.The atrial septal aneurysm was all found in neonates.Different types of arrhythmia were with different concomitant diseases:supraventricular tachycardia was associated with respiratory infection,atrial tachycardia was combined with cardiac enlargement,atrial flutter was combined with atrial septal aneurysm,supraventricular tachycardia was associated with respiratory infection,atrioventricular block was associated with myocarditis.The probability of refractory arrhythmia in supraventricular tachycardia was significantly lower than that of atrial tachycardia and atrioventricular heart-block (P<0.01).There was no difference in the incidence of refractory arrhythmia between atrial flutter and atrial tachycardia or heart-block (P=0.10). Conclusion The clinical characteristics and medication effects were different among different MA in children.The therapeutic effect of supraventricular tachycardia was superior to atrial tachycardia and atrioventricular block.