When the lung nodule is 5mm in size, if it is a pneumonic nodule, anti-infection treatment is feasible; benign nodules require regular follow-up; if it is a malignant nodule, the best eradication method is surgical resection. When a pulmonary nodule is found for the first time, the nature of the pulmonary nodule can be initially determined from two perspectives: appearance assessment and exploration, including nodule size, morphology, margins and tumor-lung interface, internal structural features, and dynamic changes on follow-up. If an inflammatory nodule is considered, most nodules will disappear with anti-infective treatment. If the nodule is considered benign, 5mm is not necessary to intervene and regular review is sufficient. If the nodule is considered malignant or if there is an increase in the diameter of the lesion during follow-up, a doubling time consistent with the tumor growth pattern, a realistic internal component or angiogenesis, the appearance of lobulation, burrs, and or signs of pleural depression, the possibility of malignancy is considered. This is when surgical resection needs to be considered. Lung nodule 5 mm, it is recommended to go to the regular hospital to clarify the diagnosis, under the guidance of the doctor’s follow-up or surgical treatment.