Preoperative neutrophil-to-lymphocyte ratio (NLR) is a new hotspot for its prognostic significance in many types of cancers. In this study, a novel diagnosing model-the combination of enhanced contrast computed tomography (ECCT) and NLR (COCT-NLR) was constructed to detect the lymph nodal involvement in patients with non-small cell lung cancer (NSCLC). The clinicopathological parameters and thoracic ECCT images of 353 NSCLC patients were retrospectively reviewed. The COCT-NLR model was constructed and evaluated in detecting regional lymph nodal metastasis in patients with NSCLC. Univariate and multivariate analyses of clinicopathological parameters revealed that NLR value was independently associated with regional nodal involvement rate in patients with NSCLC (odds ratio (OR) = 4.770; 95 % confidence interval (CI), 2.487-9.146; P < 0.001). Compared with ECCT and NLR, the COCT-NLR model showed the highest efficacy in predicting nodal involvement. The sensitivity and specificity of COCT-NLR were 70.59 and 74.89 %, respectively. The COCT-NLR model is a valuable tool in detecting regional lymph node metastasis in patients with NSCLC.