The causes of pleurisy are mainly considered as tuberculosis, infection, tumor and heart failure. 1. Tuberculous pleurisy: it is the most common cause of exudate, mostly seen in young and middle-aged people, most of them have the symptoms of dry cough, emaciation, low fever and night sweating, and the treatment needs anti-tuberculous treatment. 2. Infectious pleurisy: mostly pneumonia-like pleural effusion, the amount is usually small, anti-infective treatment is effective, the emergence of pus chest requires closed chest drainage pleural effusion. 3. Malignant pleural effusion: caused by malignant tumor invading the pleura, pleural fluid with elevated tumor markers, mostly bloody, the treatment needs to be combined with systemic therapy such as tumor chemotherapy, targeted therapy, etc., which can be locally infused with chemotherapeutic drugs. 4. Other: heart failure can have bilateral pleural effusion, hypoproteinemic pleural effusion is often accompanied by generalized edema, cirrhosis pleural effusion can be combined with abdominal effusion. Pleurisy need to consult a doctor in a timely manner, under the guidance of specialists to treat the cause.