Objective To investigate the clinical features, treatment and prognosis of tachycardia-induced cardiomyopathy (TIC) in children. Methods The clinical data of 18 hospitalized children with TIC from January 2013 to September 2020 were retrospectively analyzed and the patients were followed up. Forty children with dilated cardiomyopathy (DCM) were selected at the same time. The clinical characteristics, treatment and prognosis between TIC and DCM groups were compared. Results Among 18 children with TIC, 15 (83.3%) had atrial tachycardia and among the 15 children, 8 were persistent atrial tachycardia. The percentage of arrhythmia in total heart rate was 100% (91.9% -100%) in patients with moderate to severe left ventricular systolic function decline (n=7), and 38.7% (32.9% -99.8%) in patients with mild left ventricular systolic function decline (n=7), and the difference was statistically significant (P<0.05). All 18 patients were given drug therapy at first, 6 patients maintained sinus rhythm after drug cardioversion, and 7 of the 12 patients who could not maintain sinus rhythm after drug cardioversion underwent radiofrequency ablation, and all patients succeeded in cardioversion. The other 5 patients were given drugs to control heart rhythm and ventricular rates, and the ventricular rates decreased obviously, and the frequency and load of arrhythmia decreased significantly. Compared with the DCM group, the children in the TIC group was diagnosed at a younger age, had a faster heart rate and a larger heart rate index in the acute phase, a less frequent occurrence of moderate-to-severe heart failure, a smaller left ventricular end-diastolic dimension Z value (LVEDD-Z) after normalized body surface area at the first visit, a higher left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS), a higher percentage of atrial tachycardia, a lower ratio of ventricular tachycardia, a higher total heart rate in 24h-dynamic electrocardiogram, a higher arrhythmias percentage of total heart rate, a lower ratio of serum B-type natriuretic peptide (BNP) increase within 2 weeks of treatment, and a higher ratio of BNP before treatment to BNP within two weeks after treatment (BNP-R), and the differences were significant (P<0.05). Conclusions If the heart rate of the child increases significantly, the load of ectopic rhythm tachycardia is high, and there is impaired left ventricular systolic function and cardiac enlargement at the same time, and after cardioversion treatment or control of ventricular rate by medication, the impaired left ventricular systolic function recovers quickly and completely, and the enlarged heart shrinks significantly, the diagnosis of TIC should be considered. The overall prognosis of TIC is good.