This study aimed to analyze the prognostic significance of the positive nodal chain ratio (NCR) in non-small-cell lung cancer (NSCLC). A total of 208 pIIIa-N2 NSCLC patients who underwent complete surgical resections with a systematic nodal dissection were enrolled. The median values of NCR and the positive lymph node ratio (LNR) were used to grouping patients. The differences of overall survival (OS) and disease-free survival (DFS) between the different groups were compared. The median values of NCR and LNR were 0.31 and 0.45, respectively. The patients were separated into group A (NCR ≤0.45 and LNR ≤0.31; 91 cases), group B (NCR ≤0.45 and LNR >0.31 or NCR >0.45 and LNR ≤0.31; 51 cases), and group C (NCR >0.45 and LNR >0.31; 66 cases) according to their combined LCR and LNR values. Groups A, B, and C exhibited significantly different prognoses (5-year OS: 43.7, 25.2, and 12.3 %, respectively, p < 0.0001; 5-year DFS: 30.4, 23.3, and 8.6 %, respectively, p < 0.0001). Multivariate analyses revealed that this novel grouping method based on the combination of NCR and LNR was an independent prognostic factor for 5-year OS and 5-year DFS in pIIIa-N2 NSCLC. In group C, patients who received no postoperative treatment, adjuvant chemotherapy alone, or chemoradiotherapy exhibited different 5-year OS rates (0.0, 11.6, and 37.5 %, respectively, p = 0.003) and 5-year DFS rates (0.0, 7.5, and 25.0 %, respectively, p = 0.009). Therefore, postoperative chemoradiotherapy may significantly improve the prognosis of patients displaying NCR >0.45 and LNR >0.31. NCR combined with LNR may be more effective to guide individualized multimodality therapy including postoperative chemoradiotherapy for pIIIa-N2 NSCLC.