Inclusion Criteria:  Patient aged 18-75 years old; 6 mm ≤ tumor size ≤ 20 mm; 0.25 ≤ C/T ≤ 0.75; Center of tumor located in the middle third of the lung field; ECOG score of 0,1 or 2; Lung function (FEV1 ≥ 1 L and ≥ 70%); Both lung segmentectomy and lobectomy could achieve R0 resection; No serious cardiopulmonary complications, and could withstand both lung segmentectomy and lobectomy; No hilus pulmonis and mediastinal lymph node metastasis and no distant metastasis; Written informed consent. Single tumor nodule or the concomitant nodule < microinvasive tumor;  Exclusion Criteria:  the tumor is located in right middle lobe; a history of other malignancies in the last 5 years (exclusion of early-staged thyroid cancer and cervical cancer in situ); have received preoperative anti-tumor therapy, including prior chemotherapy, radiation therapy, target therapy and so on; serious mental illness; Pregnant and lactating women; congestive heart failure, myocardial infarction, severe stenosis of coronary artery within recent 6 months; With the history of cerebral infarction or cerebral hemorrhage within 6 months; With the history of sustained systemic corticosteroid therapy within 1 month; Other unsuitable situations;