Abstract: Objective To investigate the expression of forkhead box P3 (Foxp3) in peripheral blood of children with bronchial asthma and its relationship with airway hyper-responsiveness and body allergy. Methods A total of 80 children with bronchial asthma treated in the Affiliated Hospital of Yangzhou University from July 2024 to June 2025 were selected as experimental group, and 47 healthy children with physical examinations in the same period were selected as control group. Airway hyper-responsiveness indicators (respiratory resistance, bronchial stimulant reaction threshold, and resistance increase slope), body allergy indicatorsserum immunoglobulin E (IgE), eosinophil cationic protein (ECP), and eosinophil count (EOS), pulmonary function indicatorspeak expiratory flow (PEF), forced expiratory volume in the first second (FEV₁), forced vital capacity (FVC), and the ratio of forced expiratory volume in the first second to forced vital capacity (FEV₁/FVC), and the expression level of Foxp3 in peripheral blood were compared between the two groups. Pearson correlation analysis was used to explore the correlations of Foxp3 with airway hyper-responsiveness and body allergy. Results The respiratory resistance and resistance increase slope in the control group were significantly lower than those in the experimental group, while the reaction threshold was significantly higher than that in the experimental group (P < 0.05). The levels of IgE, ECP and EOS in the experimental group were significantly higher than those in the control group (P < 0.05). The FEV₁, FVC, PEF, and FEV₁/FVC in the experimental group were significantly lower than those in the control group (P < 0.05). The expression level of Foxp3 in the experimental group was (3.04±0.22), which was significantly lower than (4.22±0.41) in the control group (P < 0.05). Foxp3 was significantly correlated with respiratory resistance (r=-0.700, P < 0.001), reaction threshold (r=0.704, P < 0.001), resistance increase slope (r=-0.842, P < 0.001), IgE (r=0.864, P < 0.001), ECP (r=-0.684, P < 0.001), and EOS (r=-0.854, P < 0.001). Conclusion The decreased Foxp3 in peripheral blood in children with bronchial asthma is associated with aggravated airway hyper-responsiveness and body allergy, suggesting that Foxp3 may be involved in the pathogenesis of bronchial asthma.