Radiodermatitis，a common adverse reaction after radiotherapy for tumor patients，seriously affects the quality of life.Traditional Chinese medicine(TCM) with the core idea of syndrome differentiation has unique advantages in the treatment of diseases.Therefore，exploring the TCM pathogenesis of radiodermatitis can help to improve the therapeutic effect of TCM treatment.Because the clinical manifestations of radiodermatitis are similar to those caused by dryness，this paper discusses radiodermatitis from the perspective of dryness to provide a new idea for the TCM treatment.