Micronodule 3mm in the upper lobe of the right lung is usually not serious and regular review is sufficient. It is often caused by lung infections such as pneumonia and tuberculosis, but there is a possibility of developing into malignant lesions, which requires regular review and assessment. Micronodules of 3mm are very small and are mostly caused by lung infections such as pneumonia and tuberculosis. Patients usually have no special symptoms and do not require special treatment, but should follow the doctor’s instructions for regular review. In the process of regular review, through perfect chest CT examination, observe whether the shape of the nodule is regular, whether the boundary with the surrounding tissues is clear, whether there is any burr sign or lobulation sign around the nodule, observe the change of the size of the nodule, and if the situation permits, it is also feasible to do a pathological biopsy to determine whether the nodule is a benign nodule or a malignant nodule. Benign nodules are not serious, but if the nodules are considered to be malignant during the review process, then they are more serious and require early surgical removal of the nodules, and subsequent treatment as prescribed by the doctor.