Interstitial lung disease is a disease in which inflammatory infiltration and fibrotic repair of the interstitium surrounding the alveolar wall and pulmonary vessels occurs. The lesions are diffusely distributed because they occur below the 23rd level bronchi, i.e., in the periphery of the lung. Interstitial lung disease occupies an important position among lung diseases, with a wide variety of diseases and complex etiologies. A variety of etiologies can lead to interstitial lung disease, such as systemic diseases, infections, drugs, occupational factors, and environmental factors. Those with unknown etiology are called idiopathic. Idiopathic pulmonary fibrosis is the most common type of interstitial pneumonia of unknown etiology. In recent years, due to the application of high-resolution CT and advances in pathology, the level of diagnosis of this disease has been further improved. Idiopathic pulmonary fibrosis is most often seen in middle-aged and elderly patients and has an insidious onset. Patients often complain of dyspnea after activity, shortness of breath when walking upstairs or climbing hills, and it gradually worsens. It is accompanied by a dry cough. There may also be bruising of the lips and nails and deformation of the ends of the fingers in the shape of a bulge. Many patients fail to be diagnosed in time because of confusion with chronic bronchitis. Chronic bronchitis attacks tend to be seasonal, with attacks occurring in winter and spring after a cold spell and stabilizing when the weather turns warm. The cough is sputum-rich. In contrast, the symptoms of idiopathic pulmonary fibrosis gradually worsen, during which there is no significant period of remission. If middle-aged or elderly patients find the above, they should promptly visit the respiratory medicine department of a general hospital. The Department of Respiratory Medicine of our hospital has specialized doctors who specialize in interstitial lung disease in consultation. When patients visit the outpatient clinic, a chest radiograph is a routine test, and physicians often make a preliminary diagnosis based on history, signs and chest radiograph performance. Chest radiographs can show the distribution characteristics and severity of the disease in patients with idiopathic pulmonary fibrosis. To further determine the nature of the lesion, a high-resolution CT of the chest is required, which can show the fine structures of the lung more clearly than a normal CT and is an important basis for the diagnosis of idiopathic pulmonary fibrosis. In addition, blood gas analysis, lung function, fiberoptic bronchoscopy and some laboratory tests are also essential. Because the diagnosis of interstitial lung disease is complex, it is best to be hospitalized if available. Once the diagnosis of interstitial lung disease is proposed, the patient should also carefully recall the possible causes of the disease, including previous chronic diseases, smoking history, medications, exposure to dust and toxic and harmful substances at work, pet ownership, environmental factors of long-term residence and family history, and so on, in order to clarify the diagnosis of idiopathic pulmonary fibrosis one by one.