Gastric cancer is a common malignant tumor, and in recent years, the incidence of proximal gastric cancer and gastroesophageal junction adenocarcinoma has significantly increased. Multiple studies have shown that for proximal gastric cancer or gastroesophageal junction adenocarcinoma, when the tumor diameter is ≤4 cm, regardless of the depth of infiltration, the likelihood of lymph node metastasis to the No. 4, No. 5 and No. 6 groups is very low. For early proximal gastric cancer and gastroesophageal junction adenocarcinoma, proximal gastrectomy has a comparable 5-year overall survival rate to total gastrectomy. Proximal gastrectomy has advantages in preserving remnant stomach and pyloric function after operation, as well as improving the nutritional status of patients. Various reconstruction procedures are available for postoperative reflux esophagitis after proximal gastrectomy. Among them, double seromuscular flap technique has good anti-reflux effects, significantly reducing the occurrence of food residue and improving the postoperative survival quality of patients, meeting the requirements of modern gastric cancer surgery for individualization, precision, functional preservation, and quality improvement.