Pulmonary nodules of 9mm already belong to lung nodules larger than 8mm, which are generally considered more serious, while the severity of the nodules should also be judged according to their size in conjunction with the nature of the nodules. Lung nodules are generally divided into three cases: ground glass nodules, partially solid nodules and solid nodules. Nodules smaller than 5mm are generally recommended to be followed up dynamically once a year, which is not serious, while nodules of 6-8mm are followed up once every 3 months. Lung nodules larger than 8mm are already 9mm, which can suggest a more serious possibility of early lung malignancy, i.e. early lung cancer. If necessary, enhanced CT and MRI of the chest can be performed, and puncture can also be done to clarify the nature of the pathological tissue, and early surgical intervention by a thoracic surgeon is also inevitable. Lung nodules of 9mm must be taken seriously, which is already a very serious manifestation and needs to be considered for surgery.