Pleural effusion in lung adenocarcinoma would be clinically classified as stage IV, which is advanced stage. For stage IV non-small cell lung cancer, the median survival period is often 8-16 months, with a 1-year survival rate of about 30% and a 2-year survival rate of about 10%. Pleural effusion in lung adenocarcinoma requires puncture and aspiration if there is a lot of fluid, and the extracted fluid is sent for fluid-based cytology. If tumor cells are detected, chemotherapy drugs can be instilled into the chest cavity, and systemic chemotherapy is also needed in combination. If the lung adenocarcinoma has EGFR or ALK mutation, it is suitable for oral targeted drugs. Oral targeted drugs not only have mild side effects, but also have better efficacy than chemotherapy, in clinical practice, many patients can achieve long-term survival through oral targeted drugs even in advanced stage of lung adenocarcinoma.