Previous tuberculosis can still be detected as old lesions on CT after healing. Patients with old tuberculosis, which appears on CT as one or more fibrous streaks, proliferative nodules or calcified foci in the lungs and often has a positive tuberculin test, are usually not infectious and do not require anti-tuberculosis treatment but need to be reviewed regularly. Those with impaired cardiopulmonary function presenting with decreased exercise endurance may receive rehabilitation therapy. Patients who develop a low immune system can also cause a relapse of TB. In order to avoid TB relapse, the principles of early, regular, full, moderate and combined medication should be followed in the treatment. The goal of treatment is not only sterilization and prevention of drug resistance, but also final sterilization, prevention and elimination of relapse.