Malignant pleural effusion is relatively unlikely to be cured. Malignant pleural effusion is often due to the late stage of lung cancer or due to pleural mesothelioma, which is difficult to be treated completely due to the high degree of malignancy and late staging. Clinically, patients with malignant pleural effusion often need to be initially diagnosed according to their family history, predisposing factors, age, gender, etc., and the clinical analysis should be based on the results of tumor markers, such as chest-enhanced CT. For cases that are difficult to diagnose, it is often necessary to use thoracocentesis to extract fluid to look for cancer cells, look for tumor cells to assist in the diagnosis, and if necessary, thoracoscopic pleural biopsy is needed to assist in the diagnosis, and for patients with a clear causative factor to take targeted therapy. Meanwhile, for the tissues taken out from the body, corresponding immunohistochemistry and genetic testing can be done, and according to the results, corresponding chemotherapy, radiotherapy, targeted therapy, immunotherapy, etc., which can prolong the survival period of patients and improve their quality of life.