As the name implies, interstitial pneumonia is an inflammation that occurs in the interstitial space of the lungs. But interstitial pneumonia is different from ordinary bacterial pneumonia. The vast majority of interstitial pneumonia has an unclear cause and, as a result, has a poor outcome and a prognosis bordering on that of lung cancer. In the acute phase of interstitial pneumonia, there is a large infiltration of inflammatory cells in the interstitium of the lung, and chest CT shows diffusely distributed infiltrative shadows in the lung; in the chronic phase, due to the proliferation of fibroblasts, the normal lung structures are replaced by a large number of fibroblasts, resulting in loss of normal respiratory function and respiratory failure. Common medical terms: interstitial pneumonia, idiopathic interstitial pneumonia, idiopathic pulmonary fibrosis (IPF), diffuse pulmonary interstitial fibroplasia, cryptogenic pulmonary interstitial fibrosis, diffuse alveolitis, etc. Clinical manifestations: cough, often dry, shortness of breath, shortness of breath on movement (progressive dyspnea increased); chest CT shows diffuse lesions in both lungs with hairy glass-like changes. Diffuse fibroplasia with honeycomb-like changes in both lower lungs near the pleura; pulmonary function showed restrictive ventilation dysfunction and diffusion dysfunction. Auscultation: Vecrol sounds can be heard in both lungs. There are no effective drugs, but pirfenidone and nintedanib (Ofev, Boehringer Ingelheim) may be effective. A small number of patients may be stable for a long time, while most progress slowly, with some progressing rapidly and dying of respiratory failure. The main treatments: oxygen, ventilator, rehabilitation exercises and lung transplantation.