Stage 1a3 lung cancer belongs to stage I lung cancer, which is still more serious. The maximum diameter of the tumor in this stage is 2-3cm, the tumor is wrapped by the lung and pulmonary pleura, bronchoscopy can find that the tumor invades the lobar bronchus but not the main bronchus, there is no metastasis of regional lymph nodes, and there is no thoracic cavity and distant metastasis. When treating stage 1a3 lung cancer, it is important to consider whether the patient has contraindications to surgery. If the patient has no contraindications to surgery, the first choice is radical surgical resection treatment, which aims at removing the tumor and reducing tumor metastasis and recurrence. Adjuvant chemotherapy is not required after surgery, and regular postoperative review is performed. If there are contraindications to surgery, radical radiotherapy can be considered. Lung cancer can reduce the adverse effects of the disease through early detection, early diagnosis and early treatment. It is recommended to have regular medical checkups and early regular treatment after discovery.