Preoperative radiotherapy for gastric cancer is applicable to patients who cannot undergo direct surgical resection because of their condition, usually with late localized lesions or progressive gastric cancer, and some patients can regain the chance of surgery after receiving radiotherapy. For postoperative radiotherapy of gastric cancer, for R1 and R2 resection, there should be routine postoperative radiotherapy or postoperative simultaneous radiotherapy, for R0 resection, D0 or D1 resection, T2N0 patients can choose observation or postoperative radiotherapy. For patients with T3, T4 stage or lymph node metastasis, postoperative radiotherapy or postoperative simultaneous radiotherapy should be performed.Whether or not postoperative radiotherapy is needed after D2 resection is not conclusive at this time.D2 resection requires a higher degree of precision on the part of the surgeon, and it takes several years of training for the professional to be able to complete the procedure more thoroughly. If the quality of a patient’s surgery does not meet the international recommended standards for radical D2 postoperative surgery, supplemental postoperative radiotherapy is needed to consolidate the effects of surgical treatment, and patients with lymph node metastases may benefit more from subgroup analyses of large phase III clinical studies now. In addition, given the severe local tumor extravasation, patients with high local recurrence rates, T3 and T4 staging or patients with lymph node metastases, postoperative radiotherapy or simultaneous postoperative radiochemotherapy is still recommended.