Objective To investigate the clinical effect of nasal high flow humidified oxygen therapy on pulmonary interstitial fibrosis complicated with type I respiratory failure. Methods A retrospective study was conducted to include 70 patients with pulmonary interstitial fibrosis complicated with type I respiratory failure admitted to the Second People's Hospital of Gansu Province from April 2021 to September 2022. The patients were divided into control group and treatment group, with 35 cases in each group. After admission, patients in control group were given basic treatments such as anti-infection, phlegm reduction, heart rate stabilization and nutritional support according to underlying diseases. The treatment group was given high-flow humidified oxygen therapy on the basis of the control group. The clinical efficacy, vital signs, lung function and blood gas indices of the two groups were compared before and after treatment for 48 hours. Results After 48 hours of treatment, the total efficacy of the treatment group was 82.86%, which was higher than 51.43% of the control group (P<0.05).After 48 hours of treatment, the vital signs and pH of the two groups were lower than those before treatment, the improvement of HR and RR of treatment group were better than those of control group, and the pH of treatment group was lower than that of control group (P<0.05). The FEV1%, DLCO, PaCO2, PaO2 in the two groups were higher than those before treatment, and treatment group was higher than control group (P<0.05). Conclusion Nasal high?flow oxygen therapy can improve the pulmonary function and blood gas related indices in patients with idiopathic pulmonary interstitial fibrosis and type I respiratory failure, and improve the vital signs of patients, which is conducive to improve the clinical efficacy.