Objective: To identify potential predictive indicators for coronary artery lesions (CAL) in Kawasaki disease (KD) based on humoral immune markers. Methods: A total of 80 children with KD admitted to the hospital from April 2020 to December 2024 were enrolled and divided into a CAL group (n=33) and a non-CAL group (n=47) based on the presence or absence of CAL. Demographic data, routine blood tests, plasma C-reactive protein (CRP) levels, serum ferritin levels, and humoral immune markers (IgA, IgG, IgM, C3, C4, IgA/C3 ratio, IgG/C3 ratio, and IgG/C4 ratio) were collected and compared between the two groups. Results: Significant differences were observed between the CAL and non-CAL groups in CRP, ferritin, IgA, IgG, C3, IgA/C3 ratio, IgG/C3 ratio, and IgG/C4 ratio (P<0.05), while no significant differences were found in age, sex, weight, or other laboratory indicators (P>0.05). Multivariate logistic regression analysis revealed that ferritin, IgA/C3 ratio, IgG/C3 ratio, and IgG/C4 ratio were independent influencing factors for CAL (P<0.05). ROC curve analysis indicated, the AUC values for predicting coronary artery lesions (CAL) Kawasaki disease using ferritin, IgA/C3 ratio, IgG/C3 ratio, and IgG/C4 ratio were , 0.744, 0.665, and 0.528, respectively. Among these, ferritin and the IgA/C3 ratio demonstrated relatively reliable predictive efficacy (AUC > 0.7), whereas the IgG/C3 and IgG/C4 ratios showed poor predictive performance. Conclusion: The IgA/C3 ratio may serve as a potential biomarker for predicting CAL in children with KD.