With the popularity of lung CT examinations there are many people with small nodules in the lungs, at least in absolute numbers. Nodules are round, high-density lesions in the lungs less than 3 cm in diameter, and small lung nodules are those less than 1 cm in diameter. With the development of medical technology and the improvement of technical means of examination, especially the widespread use of CT technology, the discovery of small nodules in the lungs has become more and more common, and previously, because most of the ordinary chest films and chest X-rays were taken, the resolution was low and the diagnosis of lesions less than 1 cm was In the past, due to the low resolution of ordinary chest radiographs and chest X-rays, the diagnosis of lesions below 1 cm was limited. Nowadays, the resolution of lung CT can reach 1 mm and below, so the detection rate of small lung nodules is becoming higher. Of course, small pulmonary nodules are still an imaging concept and not a real disease. Small pulmonary nodules can be either benign or malignant and need to be judged comprehensively based on the corresponding medical history and CT imaging performance.