The incidence of gastric cancer ranks the 3rd and 5th among male and female tumors worldwide, and the mortality rate ranks the 2nd and 4th among male and female tumors respectively. Less than 5% of patients have early gastric cancer at the time of consultation, and more than 95% of patients have progressive gastric cancer. The radical resection rate of gastric cancer treatment is less than 50%, and the main reason for treatment failure is intra-abdominal recurrence. Major gastrectomy is recommended for distal gastric cancer. The 4 stations of lymph nodes that may metastasize from gastric cancer are divided into 16 groups. To reduce surgical complications and mortality, combined organ resection with lymph node dissection at stations 1 and 2 is no longer recommended. Preoperative radiotherapy for gastric cancer (especially cardia cancer) can significantly prolong the long-term survival rate of patients and significantly improve the resection rate; postoperative simultaneous radiotherapy has now been proven to improve the long-term survival rate and reduce the recurrence rate of patients in the progressive stage (especially when the lymph node clearance in surgery does not reach station 2 lymph nodes), and has become the standard treatment mode for postoperative gastric cancer. At present, the postoperative three-dimensional conformal radiotherapy (3D-CRT) and medical imaging-guided precise radiotherapy (IGRT) with synchronous chemotherapy in our department have achieved better efficacy and minimized the irradiation dose to the normal organs in the abdomen around the stomach, which really improves the efficacy and prolongs the survival time of gastric cancer patients in a relatively comfortable treatment process. Postoperative synchronous radiotherapy has become the standard treatment for patients with stage IB, stage II, stage IIIA, stage IIIB, and stage IV (M0).