Secondary pulmonary fibrosis refers to interstitial fibrosis of the lungs caused by known etiology, mainly including connective tissue disease-related pulmonary fibrosis, drug pulmonary fibrosis, occupational pulmonary fibrosis and other causes of pulmonary fibrosis. 1. Connective tissue disease pulmonary fibrosis: pulmonary fibrosis caused by autoimmune diseases such as scleroderma, rheumatoid arthritis and systemic lupus erythematosus. It is usually due to the autoantibodies of such patients misrecognizing and attacking the lung tissues. 2. Drug-induced pulmonary fibrosis: often due to paraquat, bleomycin and two kinds of drug-induced pulmonary fibrosis, these two kinds of drugs on the lungs to cause acute damage, the use of improper will lead to patients in a short period of time to develop pulmonary fibrosis and thus lead to death. 3. Occupational pulmonary fibrosis: pulmonary fibrosis caused by pneumoconiosis, due to long-term inhalation of harmful dust. Secondary pulmonary fibrosis is still mainly treated for the primary disease, combined with respiratory support and other symptomatic treatment to actively control the symptoms. If you suffer from this type of disease, you must be actively treated and regularly reviewed in order to prolong the patient’s life as much as possible and improve the patient’s quality of life.