Chest and abdominal fluid one year after lung cancer surgery is not necessarily a recurrence, but may also be caused by other reasons. There are many causes of hydrothorax, such as heart failure, uremia, hypoproteinemia, tuberculosis and so on. The appearance of hydrothorax and ascites can be accompanied by corresponding symptoms, such as shortness of breath, fatigue, cough, etc. The symptoms of lung cancer recurrence are mainly cough, sputum, hemoptysis, dyspnea, weight loss, fatigue and so on. To distinguish which is the cause of chest and abdominal water, chest and abdominal water can be extracted for examination, such as color, transparency, cell count, Levantine test, etc. If chest and abdominal water is bloody and tumor cells can be found in it, it suggests lung cancer recurrence. After surgical treatment, lung cancer patients need regular review so as to detect early recurrence or metastasis. Patients who have chest and abdominal water need to find out the cause of the disease first and treat it actively.