When pleural effusion occurs after lung adenocarcinoma surgery, small amount and asymptomatic ones do not need to be treated, while large amount or accompanied with infection need drainage, anti-infection and anti-tumor treatment. Small amount of pleural effusion after lung adenocarcinoma surgery is a common complication after surgery, which will not affect the cardiopulmonary function of patients and most of it will be absorbed gradually without special treatment. For patients with large amount of pleural fluid, which will affect lung function and symptoms such as chest tightness, shortness of breath, dyspnea, etc., they need to drain it in time to relieve the pressure symptoms. For pleural effusion caused by tumors, they need to give anti-tumor treatment, such as thoracic cavity perfusion chemotherapy. For patients with symptoms of infection, besides drainage, anti-infection treatment should be given, and antibiotic irrigation of chest cavity if necessary. Therefore, when pleural effusion occurs after lung adenocarcinoma surgery, it should be treated reasonably according to the specific conditions of patients.