Small 5mm lung nodules are tiny nodules and are not serious. Clinically nodules are classified into 3 types: ground glass nodules, partially solid nodules and solid nodules, with partially solid nodules having the highest degree of malignancy. If it is a ground glass nodule, it is mostly a benign chronic inflammatory change when it is less than 5mm, there is no clinical symptom, no special treatment is needed, only dynamic follow-up of chest high resolution CT once a year is needed. If the nodule is between 6-8mm and shows growth changes, it needs to be alerted to the occurrence of early lung cancer. In particular, small nodules with changes such as short burrs, lobulation, pleural traction sign and pleural depression sign should be alerted for the development of early lung cancer. Enhanced CT of the chest as well as percutaneous lung puncture cytologic biopsy should be given if necessary to find out whether the 5mm nodule has undergone early lung cancer changes. Once the diagnosis is confirmed, the thoracic surgeon can be asked to perform surgery to remove the lesion at an early stage to avoid any missed diagnosis or misdiagnosis.