PURPOSE: To investigate whether Impulse Oscillometry (IOS) could more effectively monitor children with uncontrolled asthma and evaluate small airway function changes, while establishing a prediction model in combination with fractional exhaled nitric oxide (FeNO) to assist in clinical management and treatment of asthmatic children. PATIENTS AND METHODS: A retrospective study was conducted on 203 asthmatic children who were followed up in our hospital from August 2023 to August 2024. Patients were divided into controlled asthma group (n=80) and uncontrolled asthma group (n=123). Conventional ventilatory parameters, IOS parameters, FeNO levels, and clinical data were analyzed and compared between the two groups. The optimal prediction model was established through multivariate logistic regression. RESULTS: In the uncontrolled asthma group, the respiratory system impedance at 5 hz (Z5), resistance at 5 hz (R5), the difference between resistance at 5 hz and resistance at 20 hz (R5-R20), resonant frequency (Fres), and FeNO levels were significantly higher compared to the controlled asthma group. The ratio of forced expiratory volume in one second to forced vital capacity (FEV CONCLUSION: Compared to conventional pulmonary function tests, IOS effectively identifies uncontrolled status in asthmatic children, particularly in younger patients, with higher sensitivity to small airway function changes. The model comprising R5+(R5-R20) +FeNO demonstrates clinical value in identifying uncontrolled status in asthmatic children.