A pulmonary ground glass nodule is a round or round-like ground glass structure on lung CT, which may be due to infection, vasculitis, allergy, tumor, and other etiologies. The presence of ground glass nodules in the upper lobe of the left lung, if they are less than or equal to 6mm, is usually seen as a benign lesion and is not considered serious. However, if the patient is not effectively controlled, or if the nodule continues to grow, it may have more serious effects on the organism. Clinically, glass nodules less than or equal to 5mm are not considered serious and can usually be reviewed periodically without any urgency for specific treatment. If the nodule is less than or equal to 8mm, it is necessary to determine whether surgery or other treatments are needed to prevent the nodule from continuing to develop according to the nodule’s shape, location, and the patient’s physical condition. Generally less severe, with timely treatment and recovery, the risk is less and the prognosis is better. In contrast, nodules above 8 mm have an increased risk of lung tumor and also require timely exclusion of tumor. In addition to the size of the nodule, the nature and growth rate of the nodule should be noted. If the patient’s pathological examination results show that the nodule is inflammatory, it is usually less harmful to the organism and less serious, but if the nodule is malignant, it is more serious. It is recommended that patients with a 6 mm ground glass nodule in the upper lobe of the left lung should undergo regular follow-up examinations, such as enhanced CT examinations of the chest, at intervals of 3 months or more, to confirm the growth and recovery of the nodule. If the nodule continues to grow or becomes solid inside the nodule, it should be considered as lung cancer, and a puncture biopsy or surgical excision is needed to clarify the nature of the nodule.