Calcified foci in the lower lobes of both lungs are most often seen in chronic infectious lung disease, mainly in tuberculosis infection. After regular standardized treatment of tuberculosis infection, manifestations of proliferation, fibrosis, calcification, and pleural thickening are easily formed in the lungs, especially calcification is the most common. Calcified foci in the lungs suggested by chest imaging are residual lesions caused by the once infected Mycobacterium tuberculosis, with or without treatment, and dissipated by its own absorption. Calcified lesions are benign lesions that do not require special treatment without clinical symptoms and are not prone to cancer, and the presence of calcified lesions can be detected by CT examination every year. The presence of calcified lesions does not require treatment, but only dynamic follow-up CT. If seen in long-term smokers it is recommended to quit smoking to avoid recurrent chronic bronchitis and emphysema, leading to the increase of calcified foci.