Lung nodule 5mm can be initially judged as benign or malignant from the nodule size, density, morphology, border, size change, etc., or pathologic examination should prevail. Lung nodules may be caused by malignant tumors such as bronchopulmonary carcinoma and metastatic carcinoma, or benign diseases such as misshapen tumor and tuberculosis. By the size of the nodules, generally 5mm nodules are more likely to be benign lesions, but the risk of lung cancer cannot be ruled out. Lung nodules can also be assessed on the basis of their density. Solid nodules and pure ground glass nodules are generally more likely to be benign, or may be the result of malignant tumors, while mixed nodules with both solid and ground glass components are more likely to be malignant than the first two. When the lung nodule on the film shows irregular morphology, uneven density, the presence of burrs, lobular sign, vacuolar sign, pleural pulling and other suspected malignant signs, or in the follow-up process of the nodule significantly increased in size, the solid component increases, etc., the nodule has a greater likelihood of malignant; on the contrary, if the nodule morphology is regular, the edge of the edge is clear, for the likelihood of benign. However, imaging examination can only provide a preliminary assessment of the risk of benign or malignant nodules, and puncture or surgical excision biopsy is required to determine the benign or malignant nature of the nodule, and pathologic examination is the gold standard. It is recommended that the patient consult a specialist for a preliminary assessment of the specific morphology of the nodule and, if necessary, undergo a puncture biopsy and other pathologic tests.