Pleural effusion is drawn out as yellow water, mainly because most of the pleural effusion is yellowish, with some light green. Based on the color of the pleural fluid, the benignity and malignancy of the pleural fluid can be initially determined. Generally, yellowish pleural fluid is inflammatory pleural fluid, which is benign. Routine pleural fluid and pleural fluid biochemical examination can be performed to clarify the nature of pleural fluid, and then targeted treatment can be carried out according to the nature of pleural fluid. If the pleural fluid is tuberculous, rifampin, remifentan, pyrazinamide and ethambutol should be given for treatment. If the pleural fluid is a common infection, cephalosporins should be given for treatment.