Several studies have demonstrated a positive correlation between preoperative radiotherapy dose and pathological complete remission rate (CR), with radiotherapy doses ≥5500 cGy resulting in CR close to 50%. However, the internal pelvic tissues, including the small intestine, cannot tolerate radiotherapy at a total dose of >5000 cGy. The most commonly used total preoperative treatment is 4500 cGy at 180 cGy five times a week for five weeks. The dose of preoperative radiotherapy should be controlled at 40~45Gy, which is a medium dose, and the rest period should be 6 weeks after radiotherapy, in order to wait for the radiation tissue reaction to subside, and on the other hand, to give full play to the killing effect of radiotherapy on tumor to achieve the purpose of shrinkage and stage reduction. The treatment period of neoadjuvant therapy for low rectal cancer is still inconclusive. In terms of simple radiotherapy or preoperative radiotherapy, if the unconventional segmentation method is adopted, the total amount of 25Gy radiation is completed within 7 days, and surgery is performed one week after the end of the treatment. The advantage of receiving about 45 Gy of total radiotherapy and operating 4-6 weeks after the end of radiotherapy is that radiotherapy shrinks and downstages the tumor, thus improving the radical resection and anus preservation rates [27]. 5FU/LV regimen, FOLFOX regimen and FOLFIRI regimen mostly advocate the first and fifth week of dosing, while Siroda is administered continuously from the first to the fifth week. However, Yu Baoming et al. emphasized that chemotherapy cannot be stopped after the end of radiotherapy, and advocated the continuous dosing of Herodar in small doses until surgery. This will maximize the efficacy of the combination of chemotherapy and radiotherapy in order to prevent the progression of disease and the occurrence of distant metastases as much as possible.