Background and objective The sixth edition of TNM system is hard to illuminate the survival of different tumor load precisely. This retrospective study attempted to evaluate the prognostic clinicopathologic features of non-small cell lung cancer (NSCLC). Especially we subclassified tumor sizes to validate the new T classification of international union against cancer (UICC). Methods We reviewed the clinical data of 327 stageⅠNSCLC with complete resection. Survival was analysed by Kaplan-Meier method and Log-rank test. The multivariate analysis was performed with Cox’s proportion risk model. Results The 5-year survival rate of poorly differentiated histologic grade and moderate-well differentiated histologic grade were 60.49% and 73.98% respectively (P=0.02574); The 5-year survival rate of preoperative anemia or not were 64.44% and 73.00% (P=0.0182); Tumor size was divided into ≤2 cm, 2.1 cm-3 cm, 3.1 cm-5 cm and 5.1 cm-7 cm with 5-year survival rate of 86.30%, 72.73%, 62.50% and 58.33% respectively (P < 0.0001). Conclusion Histologic grade, preoperative anemia and tumor size are the independent prognostic factors in complete resection of stageⅠNSCLC. The patients with moderate-well differentiated histologic grade, non-preoperative anemia and smaller tumor size have longer survival time. Changes in tumor size classification are to subclassify into≤2 cm, 2.1 cm-3 cm, and 3.1 cm-5 cm, which is consistent with new T-staging system protocol of UICC.