Pulmonary nodules are round or round-like shadows in the lungs smaller than 3cm, of which 1-3cm are called pulmonary nodules, 0.5-1cm are called small pulmonary nodules, and 1-5mm are called tiny pulmonary nodules. Generally, small lung nodules smaller than 6mm are not likely to become malignant, so they can be followed up regularly, usually once every six months. If there is no significant change in the nodules after 2 years of follow-up, it is not necessary to follow up very often, but only once a year. If the nodule tends to increase rapidly during the follow-up period, further examination is needed to clarify the pathological diagnosis. If the lung nodule is larger than 1 cm, it should be followed up regularly, first once every 3 months, then once every 6 months, and then once a year if there is no change.