Whether postoperative pleural effusion is normal and needs to be treated is a question that plagues many patients. Our thoracic cavity is a potential gap, and the pleura on the surface of the thoracic cavity constantly secretes fluid into the thoracic cavity, while also constantly absorbing fluid from the thoracic cavity. When the rate of secretion is greater than the rate of absorption, the amount of pleural fluid will gradually increase, along with the increase of fluid, the rate of reabsorption will also gradually accelerate until the rate of secretion and absorption reaches the same level, forming a dynamic balance, and eventually the amount of pleural fluid will be stabilized. There are many factors that affect the secretion and reabsorption rate of pleural fluid, such as trauma, inflammation, tumor, and systemic nutritional status may have an impact on it, so the situation of increased pleural fluid may occur in all these cases. But after surgery, the trauma and inflammation caused by the surgery will lead to an increase in the rate of pleural fluid production, so the dynamic balance results in an increase in pleural fluid, and this process will continue until the trauma and inflammation caused by the surgery are completely recovered and the rate of pleural fluid secretion drops back to the original level, and this recovery process This recovery process often lasts for several months, so the presence of pleural effusion in the short term after surgery is a completely normal result. For the majority of patients, this pleural effusion will probably be gradually absorbed within six months after surgery, so when the chest CT is reviewed after six months, there should not still be significant effusion. In individual patients with slow recovery or too poor nutritional status, this process may be prolonged. However, pleural effusions with the following conditions need to be taken seriously and treated in the hospital: 1, pleural effusion is too much and there is obvious pulmonary atelectasis, resulting in obvious respiratory difficulties for patients; 2, patients with fever, chest pain and other symptoms, considering intra-thoracic infection; 3, celiac disease; 4, more pleural effusions still exist after six months after surgery or the pleural effusions are absorbed and then increase again Therefore, post-thoracic surgery patients who have short-term Pleural effusion, there is no need to be overly nervous, as long as the above-mentioned conditions do not exist, there is no need for special treatment.