Radiation oropharyngeal mucositis is one of the most painful side effects of radiotherapy in patients with head and neck tumors. However, the traditional radioactive oropharyngeal mucositis grading system has the problem of poor evaluation consistency. To solve this problem, we innovatively classify radiation oropharyngeal mucositis into four types according to the four-stage histopathological changes of acute radiation injury: (1) congestive; (2) Scattered erosion type; (3) Fusion erosion type; (4) Ulcer type. We intend to conduct a multicenter observational cohort study to compare the consistency of different physicians in the assessment of radiation oropharyngeal mucositis with new and traditional classifications, and to explore changes in blood markers of different types of oropharyngeal mucositis using clinical residual blood samples.