Pulmonary nodules are classified into three conditions: ground glass nodules, partially solid nodules and solid nodules. The more common ground glass nodules need to be judged according to the size and nature of the nodule to determine its degree of benignity and malignancy. Generally speaking, nodules of about 5mm are mostly benign and belong to the category of microscopic nodules, suggesting chronic lung infection, and do not require special treatment when there are no clinical symptoms. If the 5mm nodules show growth changes, and are larger than 8mm with lobar, short burr, pleural depression sign and other changes, we should be alert to the fact that 5mm ground glass nodules have changed into early stage lung cancer, and further enhanced CT examination of the chest is needed, or percutaneous lung aspiration histological examination can be given, and if necessary, a thoracic surgeon can be asked to remove the lesion to clarify whether it is early stage lung cancer as soon as possible.