Radiation therapy is widely used for thoracic cancers. However, it occasionally causes radiation-induced lung injuries, including pneumonitis and fibrosis. Chung-Sang-Bo-Ha-Tang (CSBHT) has been traditionally used to treat chronic pulmonary disease in Korea. PM014, a modified herbal formula derived from CSBHT, contains medicinal herbs of seven species. In our previous studies, PM014 exhibited anti-inflammatory effects in a chronic obstructive pulmonary disease model. In this study, we have evaluated the effects of PM014 on radiation-induced lung inflammation. Mice in the treatment group were orally administered PM014 six times for 2 weeks. Effects of PM014 on radiation pneumonitis were evaluated based on histological findings and differential cell count in bronchoalveolar lavage fluid. PM014 treatment significantly inhibited immune cell recruitment and collagen deposition in lung tissue. Normal lung volume, evaluated by radiological analysis, in PM014-treated mice was higher compared to that in irradiated control mice. PM014-treated mice exhibited significant changes in inspiratory capacity, compliance and tissue damping and elastance. Additionally, PM014 treatment resulted in the downregulation of inflammatory cytokines, chemokines, and fibrosis-related genes and a reduction in the transforming growth factor-β1-positive cell population in lung tissue. Thus, PM014 is a potent therapeutic agent for radiation-induced lung fibrosis and inflammation.