Background: Severe pneumonia complicated by myocardial damage is a serious condition in children, and early prediction and intervention are crucial for improving outcomes. To explore the clinical value of serum hyaluronic acid, procollagen III N-terminal propeptide, sST2, and cfDNA levels in predicting myocardial damage in children with severe pneumonia. Methods: A case-control study was conducted on 140 children with severe pneumonia, divided into a control group (n=70) and a group with disease complicated by myocardial injury (n=70). Biomarker levels (hyaluronic acid, procollagen III, N-terminal propeptide levels, sST2, and cfDNA) were detected through biochemical analysis, and clinical outcomes were compared between the two groups. Results: Logistic regression analysis identified hypoalbuminaemia, age