Objective To analyze the correlation between serum levels of galectin-13 (Gal-3), serum amyloid A protein(SAA), interleukin-33 (IL-33) and the severity of allergic asthma in children. Methods A total of 102 children with allergic asthma in Xuchang People's Hospital from September 2021 to June 2023 were selected as the study group, and 102 healthy children in the same period and at the same age were selected as the control group. The serum levels of Gal-3, SAA, IL-33, pulmonary function [forced vital capacity (FVC), peak expiratory flow (PEF)], and exhaled nitric oxide (FeNO) were compared between the two groups. The correlations of serum Gal-3, SAA, IL-33 levels with pulmonary function, FeNO, and disease severity were analyzed. Results The levels of serum Gal-3, SAA and IL-33 in the study group were higher than those in the control group (P < 0.05). PEF and FVC in the study group were lower than those in the control group, and FeNO was higher than that in the control group (P < 0.05). The serum levels of Gal-3, SAA, and IL-33 in mild children were lower than those in moderate and severe children (P < 0.05). PEF and FVC in the mild group > moderate > severe, FeNO mild < moderate < severe (P < 0.05). Serum levels of Gal-3, SAA and IL-33 were negatively correlated with PEF and FVC, and positively correlated with FeNO and disease severity (P < 0.05). Conclusion The levels of serum Gal-3, SAA and IL-33 in children with allergic asthma are up-regulated, which are closely related to lung function, airway inflammation and disease severity, and have important clinical significance in judging the severity of the disease.