Pulmonary fibrosis is a state in which damage to normal alveolar tissue leads to structural abnormalities through abnormal repair Scar formation is classified into two types: primary pulmonary fibrosis and secondary pulmonary fibrosis. Secondary pulmonary fibrosis, whose cause is found through relevant tests, has a better prognosis through treatment of the primary disease. The median survival of idiopathic pulmonary fibrosis is about 2-3 years, and its progression and outcome vary greatly from individual to individual: common pulmonary fibrosis is a chronic progressive predictable decline in lung function, with recurrent acute exacerbations in a minority of patients and acute rapid progression in a very small number of patients.