The disappearance of pulmonary nodules after quitting smoking is further determined by a combination of the size and nature of the nodules. There are 3 types of nodules: ground glass nodules, partially solid nodules and solid nodules. If the nodule is a ground glass nodule, less than 5 mm, it is mostly a benign chronic inflammatory nodule, and the nodule can disappear after quitting smoking. If the ground glass nodule is larger than 6-8 mm or even more than 8 mm, accompanied by short burrs, lobulation, pleural traction sign, pleural depression sign and other early lung cancer changes, further enhanced CT examination of the chest is needed. If necessary, percutaneous lung aspiration cytohistological biopsy is given to evaluate whether early lung cancer occurs. Once early-stage lung cancer occurs, the nodules do not disappear even after quitting smoking. Some of the solid nodules are the most malignant, and dynamic observation of the nodules is needed after quitting smoking. If the nodules show growing changes, especially if they are larger than 8 mm or more, you need to be alert to the possibility of early-stage lung cancer. In conclusion, benign nodules have the potential to disappear after quitting smoking, while malignant nodules do not disappear.