After breast-conserving surgery for ductal carcinoma in situ, whole-breast radiotherapy and tumor bed addition are chosen according to high and medium low risk. Ductal carcinoma in situ is categorized into ductal carcinoma in situ and lobular carcinoma in situ. Lobular carcinoma in situ has a lower risk of developing into invasive carcinoma; whereas ductal carcinoma in situ is treated with either total mastectomy or breast-conserving mastectomy, and radiotherapy is required after surgery. For those with ductal carcinoma in situ undergoing breast-conserving mastectomy, if the lesion is detected by molybdenum screening, the lesion is ≤2.5cm, the margin is ≥3mm, and the low-intermediate grading is low-risk, whole-breast radiotherapy is recommended, and radiotherapy with a large segmentation plan for part of the breast or exemption from radiotherapy can also be considered. If age ≤50 years, histologic grading 3, margin <2mm or margin positive are high-risk patients, 4 to 8 additional tumor-bed add-on radiotherapy sessions to whole-breast radiotherapy are required. Those who are neither high-risk nor low-risk are intermediate-risk patients and can be treated with whole-breast radiotherapy only. It is recommended to fully communicate with the specialist to choose the appropriate radiotherapy program according to the lesion, systemic condition and individual needs.