When small pulmonary nodules are found, the benignity is usually determined by the following: 1. The smoothness of the nodule margins is observed by imaging findings. Smooth margins with more isolated round nodules are more likely to be benign. Nodule edges that are not smooth, along with lobulation, burr or with vascular entanglement or traction, or with adhesions or traction with the pleura, are important bases for determining malignant nodules. Under normal circumstances, doctors will analyze and follow up dynamically according to the patient’s nodules and compare them several times; 2. Judging benign and malignant nodules in the lung also depends on the clinical experience of professional doctors.