Lung adenocarcinoma presenting with pleural fluid is generally stage IV. Lung adenocarcinoma is a relatively common malignant tumor of lung, and patients with lung adenocarcinoma presenting with pleural fluid (fluid staying in the thoracic cavity) are considered to have pleural metastasis, and the staging belongs to stage IV. In this period, patients have lost the chance of surgical treatment. Genetic test can be conducted, if there is gene mutation, target therapy such as gefitinib and ositinib can be given, and without gene mutation, chemotherapy or immunotherapy such as pemetrexed, cisplatin, etc. can be given to improve the survival treatment and prolong the survival period. Chest fluid extraction can also be carried out if more chest fluid affects breathing. Lung cancer patients with pleural fluid should go to the oncology department of regular hospital in time to improve the examination and follow the doctor’s instruction to do their best over the standardized treatment, so as to avoid delaying the condition.