The first step in the treatment of pulmonary nodules is to understand the causes of pulmonary nodule formation. Lung nodule formation can be roughly divided into three major categories, tumor-related lung nodules, infection-related lung nodules, and immune-related lung nodules. For the three causes, if it is a tumor-related lung nodule, benign tumor lung nodules grow slowly and in principle do not require excessive treatment; if it is a malignant-related lung nodule, such as lung cancer, the optimal early treatment is surgical resection; if it is an infection-related lung nodule, the first thing to do is to clarify whether the infection pathogen is bacteria, fungi, viruses, or parasites, and the corresponding treatment can be taken after the pathogen is clarified in order to have better results; for immune-related lung nodules, it may be necessary to take the appropriate treatment. In the case of immune-related pulmonary nodules, treatment related to immunotherapy may be required, and different treatment methods should be adopted for different causes of nodule formation.