The aim of this study was to determine the expression of IL-35 and the lymphatic vessel density (LVD) and microvessel density (MVD) in the pathological tissues from patients with non-small cell lung cancer (NSCLC) and to analyze their correlation with other common clinical prognostic factors, as well as patients' overall survival and progression-free survival. We analyzed the pathological characteristics of 130 patients with NSCLC and determined the IL-35 expression, MVD, and LVD changes in the pathological tissues by immunohistochemistry. The results showed that IL-35 expression was significantly correlated with tumor differentiation, lymph node metastasis, T staging, LVD, and MVD (P < 0.05) but was not associated with age, sex, smoking, and other factors. Univariate analysis of risk models showed that age, lymph node metastasis, T stage, and high IL-35 expression, LVD, and MVD were significantly associated with NSCLC prognosis (P < 0.05), whereas sex, smoking, and high differentiation were not correlated with prognosis. Multivariate analysis of the proportional risk model showed that the IL-35 expression, lymph node metastasis, high LVD, and high MVD were significantly correlated with NSCLC prognosis (P < 0.05). In conclusion, IL-35, MVD, and LVD may be independent prognostic markers. In addition, IL-35 might represent a promising clinical drug target for the treatment of NSCLC.