The characteristics of the cerebrospinal fluid in tuberculous meningitis are mainly the following, the cerebrospinal fluid in tuberculous patients is different at different stages of the patient’s disease course. In the early stages, the cerebrospinal fluid may be clear in appearance. As the disease progresses, when the cerebrospinal fluid is reviewed, it may appear cloudy in appearance or have a gross glassy appearance, and then a thin film may form on the surface of the cerebrospinal fluid after it has been left in place for a few hours. After lumbar puncture, the pressure of the cerebrospinal fluid is very high, which can reach 300-400 mmH2O, and the number of cells in the routine test is increased, which can reach several dozens to several hundred. In the early stage, neutrophils are predominant, and as the disease progresses, lymphocytes are predominant in the recovery phase. Sugar and chloride levels will decrease, especially chloride levels will be lower, the ratio of glucose in the cerebrospinal fluid to glucose in the blood is usually less than 0.5, and protein levels will be mildly to moderately increased, around 1-2g.