Objective To analyze the related influencing factors of infectious mononucleosis (IM) complicated by myocardial damage in children and provide scientific basis for clinical diagnosis and treatment.Methods A total of 116 children with IM, admitted to the Children’s Hospital of Baoji Maternal and Child Health Hospital from February 2023 to February 2024, were retrospectively selected as the subjects of this trial. According to the occurrence of myocardial damage in the children, they were divided into myocardial damage groups (n = 25) and no myocardial damage group (n = 91). The general information, clinical symptoms and signs, liver function, blood routine, immune function, myocardial enzyme spectrum and electrocardiogram of the two groups of patients were compared. Logistic regression was used to analyze the risk factors for myocardial damage in patients with IM.Results Compared with patients in the non-myocardial damage group, the myocardial damage group had a higher proportion of children with clinical manifestations (chest tightness, chest pain, tachycardia), electrocardiogram (ST changes, T fluctuations, ST-T changes) (P < 0.05), and had better immune function. Indicators (IgA, IgG, CD4^+/, CD8^+/, CD4^+/CD8^+/, EBV DNA) and ALT levels were higher (P < 0.05). Season of onset, clinical manifestations (angina, swollen lymph nodes, eyelid edema, hepatomegaly, splenomegaly, rash, dull heart sounds), blood routine, and liver function indicators (γ-GT, ALP, TBiL, DBiL) of the two groups ) and IgG, the differences were not statistically significant (P > 0.05). Logistic regression analysis results showed that increased EBV DNA load [O^R =3.623, (95% CI: 1.284, 10.222) ] is a risk factor for myocardial damage in children with IM (P < 0.05).Conclusion EBV DNA Elevated load is a risk factor for complicated myocardial damage in children with IM. Monitoring and early intervention of this high-risk group should be strengthened to reduce the incidence of myocardial damage and improve the prognosis of children.