The purpose of this study was to investigate the correlation between the expression of cystathionine β-synthase (CBS) in lung squamous cell carcinoma (LUSC) and the microvascular density (MVD) and clinicopathological features. Firstly, the expression status of CBS in diffuse carcinoma and LUSC was searched through the public bioinformatics database. Subsequently, immunohistochemical staining and scoring were performed on tumor tissues and matched normal tissues from 108 LUSC patients to assess CBS expression; the MVD of tumor tissues was also detected. The results showed that CBS was overexpressed in some tumor tissues, including LUSC. Immunohistochemical results showed that the positive expression rate of CBS in tumor tissues (63.0%) was higher than that in normal tissues (17.6%). The expression of CBS was correlated with T (p = 0.01), N (p = 0.004), TNM (p = 0.011) stages, and tumor differentiation degrees (p < 0.001), with the increase of T, N, and TNM stages or the decrease of differentiation, the expression level of CBS also increased. In addition, the expression level of CBS was positively correlated with MVD (r = 0.6997, p < 0.0001). Survival analysis showed that the survival rate of the CBS negative expression group was better than that of the positive expression group (p = 0.004). Cox multivariate analysis showed that CBS expression status (p < 0.001), T stages (p = 0.020), and TNM stages (p = 0.021) were independent factors affecting the prognosis of LUSC. In conclusion, the high expression of CBS affects tumor development and is associated with the poor prognosis of LUCS, which may be used as a biomarker to evaluate prognosis and find a new direction for the treatment of LUSC.