The morbidity and mortality of lung cancer are still the highest among all malignant tumors. Radiotherapy plays an important role in clinical treatment of lung cancer. However, the effect of radiotherapy is not ideal due to the radiation resistance of tumor tissues. Abnormalities in tumor vascular structure and function affect blood perfusion, and oxygen transport is impeded, making tumor microenvironment hypoxic. Tumor hypoxia is the major cause of radiotherapy resistance. By promoting tumor vessel normalization and enhancing vascular transport function, tumor hypoxia can be relieved to reduce radiotherapy resistance and increase tumor radiotherapy sensitivity. In our previous study, a pericytes-targeted tumor necrosis factor alpha (named Z-TNFα) was first constructed and produced by genetically fusing the platelet-derived growth factor receptor β (PDGFRβ)-antagonistic affibody (Z) to the TNFα, and the Z-TNFα induced normalization of tumor vessels and improved the delivery of doxorubicin, enhancing tumor chemotherapy. In this study, the tumor vessel normalization effect of Z-TNFα in lung cancer was further clarified. Moreover, the tumor hypoxia improvement and radiosensitizing effect of Z-TNFα were emphatically explored in vivo. Inspiringly, Z-TNFα specifically accumulated in Lewis lung carcinoma (LLC) tumor graft and relieved tumor hypoxia as well as inhibited HIF-1α expression. As expected, Z-TNFα significantly increased the effect of radiotherapy in mice bearing LLC tumor graft. In conclusion, these results demonstrated that Z-TNFα is also a promising radiosensitizer for lung cancer radiotherapy.