With the increasing popularity of chest CT physical examinations, the detection rate of lung nodules is increasing. When a lung nodule is detected, the treatment and examination methods are decided mainly depending on the size and shape of the nodule. The size is important. Generally, nodules less than 5 mm in diameter are more likely to be benign and require no special treatment, with regular follow-up (e.g., 3 months, 6 months, 1 year) of review of lung CT, etc. For nodules larger than 5mm, we should pay full attention to them and routinely perform tumor marker examination to make a preliminary judgment of benign and malignant degree based on the size, morphology, density, presence of burrs around the nodule, and presence of microvascular changes in the lung CT. In particular, those with previous history of other malignant tumors and new small nodules should undergo close dynamic review of CT lung to observe whether there is any change in the nodules, and usually the review of CT chest should be followed up for 2-3 years. If the nodule has changed or the degree of benignity or malignancy cannot be determined, thoracoscopic surgery can be performed to remove the nodule if necessary.