Patients with tuberculous pleurisy usually need to be carefully differentiated from patients with malignant pleural fluid. Tuberculous pleural fluid occurs more often in young and middle-aged patients, mostly with an acute onset, high fever, usually without hemoptysis, intermittent chest pain, to a lesser extent, associated with breathing and coughing, with a small to moderate amount of fluid, less often with pulmonary atelectasis, and slow progression of disease. Adenosine deaminase is often greater than 45 U/L, carcinoembryonic antigen values are normal, PPD test is positive, and antacid bacteria can be found in the pleural fluid or tuberculosis bacteria can be cultured. Patients with malignant pleural fluid, 2/3 of whom are elderly, have a slow onset, usually without fever, often accompanied by hemoptysis, with persistent and severe chest pain, with a large amount of pleural fluid and fast growth, often accompanied by pulmonary atelectasis, with rapid progression of disease. However, the differentiation between the two is often more complicated and difficult to judge than the above-mentioned cases. At this time, more comprehensive examinations, such as chest enhancement CT and thoracoscopic biopsy, should be conducted in hospitals to avoid misdiagnosis and delay in treatment.