Abstract: Objective To analyze the correlation of the expression levels of vitamin A and 25-hydroxyvitamin D 25(OH)D with pulmonary function and disease severity in children with asthmatic bronchitis (AB). Methods A total of 170 children with AB were enrolled in AB group, and another 170 healthy children who underwent health check-ups during the same period were selected and included in healthy group. The levels of vitamin A and 25(OH)D, along with pulmonary function-related indicatorsforced vital capacity (FVC), forced expiratory volume in one second (FEV₁) and the ratio of forced expiratory volume in one second to forced vital capacity (FEV₁/FVC) were measured and compared between the two groups. The severity of the disease in children with AB was evaluated and classified into mild, moderate and severe groups. Pearson correlation analysis was employed to examine the correlation between vitamin A, 25(OH)D and pulmonary function indicators, as well as their relationship with disease severity. Results The levels of vitamin A and 25(OH)D in the AB group were significantly lower than those in the healthy group (P < 0.05). The FVC, FEV₁ and FEV₁/FVC in the AB group were significantly lower than those in the healthy group (P < 0.05). The levels of vitamin A and 25(OH)D in patients with severe AB were significantly lower than those in the moderate group, which were significantly lower than those in the mild group (P < 0.05). In AB patients, the levels of vitamin A and 25(OH)D were positively correlated with FVC, FEV₁ and FEV₁/FVC, and negatively correlated with disease severity scores (P < 0.05). Conclusion Children with AB exhibit lower levels of vitamin A and 25(OH)D, which are positively correlated with pulmonary function-related indicators. The levels of vitamin A and 25(OH)D are closely related to the severity of AB in children, suggesting that they may serve as biomarkers for evaluating the condition and prognosis of children with AB.