Lung nodule 9mm has a lower chance of malignancy, which also needs to be determined by combining the nature of the nodule, imaging characteristics, etc. Specific recommendations are assessed and determined by the doctor. According to the Chinese expert consensus on the diagnosis and treatment of lung nodules, lung nodules of 5-10mm in size are distinguished between high-risk and low-risk nodules based on the nature of the nodule, the presence of adverse signs such as burr sign and pleural pulling, as well as the presence of a history of prolonged heavy smoking, a family history of tumors, a history of lung diseases, and a history of high-risk environmental exposure. The general probability of malignancy for a lung nodule of 8-20 mm is around 18%. Surgery is not recommended immediately after the first discovery of a pulmonary nodule. For a 9 mm pulmonary nodule, it is recommended to repeat the chest CT examination in 3 months to assess the change in nodule size, and empirical antimicrobial therapy can be performed as appropriate. The next step in the treatment plan is based on the follow-up of the nodule. The overall probability of malignancy for a 9-mm nodule is low, and it is recommended that the nodule be reviewed by the primary care physician in a timely manner to assess the nodule’s risk classification and formulate a treatment plan.