There are many patients with prolonged fever that does not go away despite active examination and treatment, and the patient suffers from pain and anxiety of not being able to identify the cause. The same situation often plagues our infectious disease physicians. The cause of fever in this group of patients often requires identification of the presence or absence of tuberculosis. The traditional methods to confirm the diagnosis of tuberculosis include antacid staining of smears, culture of Mycobacterium tuberculosis and histopathological examination, but the detection rate of antacid staining is low and the culture of Mycobacterium tuberculosis takes a long time, which often delays the diagnosis. However, the PPD test is often influenced by various factors such as BCG vaccination and patient immunity, resulting in low sensitivity and specificity in determining tuberculosis. In recent years, a new method of TB diagnosis based on TB antigen-specific T-cell reaction, namely T-SPOT-TB, has been gradually gaining attention and has started to be applied in clinical work. t-SPOT-TB has good sensitivity and specificity in the diagnosis of TB infection and has been recognized and applied in clinical diagnosis in more and more countries. Some studies have shown that the sensitivity of T-SPOT-TB for active TB is as high as 90%, especially for extrapulmonary active TB up to 94%, while the sensitivity of PPD test is only 47%; in addition, foreign studies have shown that the specificity of T-SPOT-TB for TB is as high as 93%. Based on the characteristics of the concentration of TB antigen-specific T cells at the lesion site, the detection of T-SPOT-TB technology is not only limited to venous blood, but also bronchoalveolar lavage fluid, sputum, chest and abdominal fluid, and cerebrospinal fluid can be used for the diagnosis of intrapulmonary and extrapulmonary TB.