Objectives：To assess the airway function of the patients with interstitial lung disease（ILD）using the conventional lung function test and the impulse oscillometry system（IOS）. Methods：Totally 129 patients with ILD and 143 coughing patients were included for the assessment. The ILD patients were all non-smokers and of connective tissue disease-associated interstitial lung disease（CTD-ILD）or interstitial pneumonia with autoimmune features（IPAF）. Lung function test results were compared between the two groups. Correlations of the diffusion capacity of the lung for carbon monoxide（DLCO）with other parameters were analyzed. Results：Restrictive and obstructive ventilation dysfunctions were observed in 51.2% and 2.3% of the patients with ILD，respectively. The vital capacity（VC），forced vital capacity（FVC），residual volume（RV）and total lung capacity（TLC）of the patients with ILD were significantly lower than those of the control group，but the forced expiratory volume in one second/forced vital capacity（FEV1/FVC）in the ILD patients was higher，which is of statistical significance（P < 0.05）. Residual volume/total lung capacity（RV/TLC）was similar in two groups（P > 0.05）. Maximal mid-expiratory flow（MMEF75/25）in the ILD group is higher but the difference is statistically insignificant（P > 0.05）. IOS airway resistance values are similar in two groups（P > 0.05）. DLCO is positively correlated with VC，FEV1，MMEF75/25，RV，TLC（P < 0.05），but negatively correlated with R5-R20，R5-R10（P < 0.05），and shows no correlation with FEV1/FVC. Conclusion：In non-smoking patients with CTD-ILD and IPAF，the restrictive ventilation dysfunction is overwhelmingly common compared with obstructive dysfunction. IOS is of no value in diagnosing ILD. With the progression of ILD and the declination of DLCO，the measured distal airway resistances using IOS show slight increase，but FEV1/FVC remain unchanged，suggesting air retention is unlikely and it is generally unnecessary to use bronchodilators during the course of CTD-ILD and IPAF.