Withdrawal of pleural effusion is a symptomatic treatment for large amounts of pleural effusion. This alone does not determine the severity of the condition, and needs to be combined with the primary disease causing the pleural effusion. Common pulmonary diseases causing pleural effusion include pleural inflammation (tuberculosis, pneumonia), pleural tumor (metastasis of malignant tumors, mesothelioma), pulmonary infarction, subphrenic abscess, etc. 1. Pleural effusion is caused by pleural inflammation, which can be cured after treating the primary disease. Tuberculosis combined with pleural effusion should be given anti-tuberculosis treatment and pleural effusion should be drained as soon as possible to avoid adhesion. 2. Pleural tumor causing pleural effusion, mostly malignant pleural effusion, pleural effusion is mostly bloody, large in volume and rapid in growth, which can lead to respiratory distress or even death due to large amount of fluid compression, which can be treated by surgery, radiotherapy and chemotherapy. 3. The pleural effusion caused by subphrenic abscess is mostly purulent pleural effusion, actively control the infection, drain the effusion, and at the same time, give supportive treatment and strengthen the nutrition to help the condition improve. There is no need to panic when pleural effusion occurs, and relevant examinations should be completed to clarify the primary cause of the disease and actively treat it.