Lung cancer is considered as the leading cause of cancer-related mortality worldwide. Non-small cell lung cancer (NSCLC) accounts for about 85% of primary lung cancer. Owing to the improved utilization of medical technological level and the popularization of health examinations, the detection rate of early-stage NSCLC is gradually increasing. The main treatment modalities for early-stage NSCLC are surgical resection and adjuvant chemotherapy. Platinum-based chemotherapy is recommended as the standard postoperative adjuvant treatment for patients with completely resected stageⅡ-ⅢA NSCLC. However, adjuvant therapy remains a controversial option in stageⅠB NSCLC. This review focuses on postoperative adjuvant therapy such as adjuvant chemotherapy, targeted therapy, and immunotherapy for completely resected stageⅠB NSCLC. Moreover, the biomarkers and prognostic factors of high-risk patients are discussed.