Researchers believed that Postoperative radiation (PORT) could increase overall survival (OS) in patients with pN2 NSCLC who have a high lymph node ratio (LNR). From 2004 to 2016, the National Cancer Database was searched for non-metastatic pN2 NSCLC patients who had R0 surgery and adjuvant treatment. The influence of PORT and LNR on OS was assessed using Cox models that were adjusted for patient variables and treatment information. PORT was found in 1,728 (42.7%) of the 4,050 patients. In patients who got PORT with known RT modality information, IMRT was used more frequently in recent years (53.8% in 2010-2016 vs. 24.0% in 2004-2009). Patients with higher LNR were more likely to obtain PORT (OR=1.51 and 1.71, P<0.001 for LNR 15-29% and ≥30%, respectively). Higher LNR was linked with worse OS (HR=1.26 and 1.96; P<0.005 for LNR 15-29% and ≥30%, respectively). In the entire cohort, PORT was linked to improved OS. PORT enhanced overall survival (HR=0.91, P=0.058) in patients with insufficient lymph node dissection (LND). Patients with LNR less than 15% (HR=1.11, P=0.21) or LNR 15-29% (HR=1.03, P=0.73) did not benefit from PORT, whereas those with LNR of more than or equal to 30% (HR=0.83, P=0.006) benefitted. IMRT significantly increased OS in patients with LNR by more than or equal to 30% when compared to no PORT (HR=0.75, P<0.05), whereas 3D RT did not (HR=0.89, P=0.32). Following accounting for many variables, PORT was related to increased survival for pN2 NSCLC patients after R0 resection, acceptable LND with high LNR. Patients with insufficient LND, excessive LNR, or use of IMRT accounted for the majority of the OS advantages of PORT throughout the entire cohort. The role of adjuvant radiation in pathological N2 (pN2) non-small cell lung cancer (NSCLC) patients after adjuvant chemotherapy is a source of debate. The lymph node ratio (LNR) was used to predict lung cancer survival. After adjuvant chemotherapy with high LNR or inadequate lymph node removal, investigators discovered that adjuvant radiotherapy, particularly intensity-modulated radiation treatment (IMRT), had survival benefits in pN2 NSCLC patients. These could be additional criteria for deciding who should receive adjuvant radiotherapy.