Objective: To explore the effect of oral levocarnitine supplementation in pediatric patients with dilated cardiomyopathy (DCM). Methods: A total of 45 children with DCM were divided into two groups according to a simple randomization: control group (n=20) and experimental group (n=25). All children were given conventional therapy. Patients in the experimental group received add-on treatment with oral levocarnitine. The duration of treatment was 1 year. Left ventricular ejection fraction (EF), short axis shortening (FS), left atrium diameter increments values (LADIV) and left ventricle diameter increment values (LVDIV) and adverse effects were recorded. Results: There was no significant difference in age, sex, cardiac function grade, EF, FS, LADIV and LVDIV between the two groups before treatment (P>0.05). One year after treatment, EF in the experiment group increased [(61.8±11.7)% vs (43.4±6.8)%, P=0.034]. FS, LADIV and LVDIV did not show significant difference compared with the control group (P>0.05). After treatment, EF [(61.8±11.7)% vs (41.4±6.2)%] and FS [(24.5±7.1)% vs (21.3±5.2)%] increased, LADIV [(3.4±0.8) mm vs (5.9±0.9 mm)] and LVDIV [(4.8±0.9) mm vs (9.7±4.2 mm)] decreased compared to the same group before the treatment (P<0.05). EF, FS, LADIV and LVDIV in the control group had no significant changes before and after treatment (P>0.05). No adverse drug reactions were observed in the two groups within one year of follow-up. Conclusion: Oral administration of levocarnitine can improve the cardiac function of children with DCM and is safe for drug treatment, which is worthy of clinical promotion.