Objective:To investigate the effects of intensity modulated radiation therapy (imRT) and risk factors of radiation pneumonia caused by imRT in elderly patients with esophageal cancer.Methods:The clinical data of 80 elderly patients diagnosed with esophageal cancer and performed imRT in Traditional Chinese Medicine Hospital of Kunshan from February 2018 to February 2020 were analyzed, and the therapeutic effect and the incidence of adverse reactions were counted.Results:In the 80 patients, 13 patients occurred radiation pneumonia.The results of univariate analysis showed that the gender, smoking history, pathological stage and age had no correlation with radiation pneumonia ( P> 0.05), while tumor location, diabetes, concurrent chemotherapy, reradiotherapy and chronic obstructive pulmonary disease had correlation with the occurrence of radioactive pneumonia ( P<0.05). The levels of V30, V35, V40 between radioactive pneumonia patients and non-radioactive pneumonia patients had no significant differences ( P>0.05), but the levels of V5, V10, V15, V20 and mean lung dose(MLD) between radioactive pneumonia patients and non-radioactive pneumonia patients had significant differences ( P<0.05). The effect of imRT was no remission in 9 cases (11.25%), partial remission in 59 cases (73.75%) and complete remission in 12 cases (15.00%), and the clinical effective rate was 88.75%(71/80). By comparing the adverse reactions caused by imRT, it was found that the incidence of radiation esophagitis, leukopenia, and acute radiation pneumonia were 93.75%(75/80), 12.50%(10/80) and 22.50%(18/80), respectively, with grade 1 and grade 2 adverse reactions. Conclusions:Risk factors for radiation pneumonia in elderly patients with esophageal cancer after imRT include tumor location, diabetes, V5, V10, V15, V20, MLD, concurrent chemotherapy, reradiotherapy and chronic obstructive pulmonary disease.