To discuss the feasibility and safety of modified side overlap with fundoplication by Yamashita (mSOFY) in laparoscopic proximal gastrectomy. Using the method of descriptive case series study, the clinical data of 9 patients with upper gastric cancer who successfully performed mSOFY anastomosis from March 2022 to October 2022 in the Affiliated Huaian No.1 People’s Hospital of Nanjing Medical University were retrospectively analyzed.The reconstruction steps of mSOFY anastomosis are as follows: (1) Make a small incision on the right side of the esophageal stump and in front of the anterior wall of the gastric stump; (2) The 45mm linear cutting stapler is placed into the preset anastomosis of the esophagus and the remnant stomach, and the esophagus is rotated 90° counterclockwise along the axis, so that the right wall of the esophagus is anastomosed with the remnant stomach, and the stomach wall is sutured to the left side of the esophagus; (3) The common opening of esophagus and remnant stomach was sutured with inverted suture; (4)Suture the left and lower sides of the esophagus with the remnant stomach to make the esophagus flat against the stomach wall; (5) Open the sutured common opening: due to the pressure of the false dome, the posterior wall of the lower esophageal segment was compressed into a valve-like structure. We mainly observing the postoperative reflux and nutritional improvement of the patients, and recording the intraoperative situation and postoperative complications. Nine patients with upper gastric cancer who completed laparoscopic proximal gastrectomy (mSOFY anastomosis) did not have conversion to laparotomy or intraoperative / postoperative complications. The operation time was (169.4±10.4) minutes, the anastomotic reconstruction time was (51.7±7.1) minutes, the intraoperative bleeding volume was (98.9±43.4) ml, and the number of lymph nodes dissected was (27.2±6.7). The patient recovered well after operation, without any complaints related to reflux esophagitis. Postoperative gastrointestinal radiography showed that the anastomosis was smooth, without stenosis and leakage. The serum albumin [(41.6±3.4) L vs. (39.9±2.6) L], prealbumin [(211.3±38.6) mg/L vs. (205.3±36.0) mg/L], and hemoglobin levels [(126.7±13.2) g/L vs. (121.0±9.7) g/L] of patients before and one month after surgery have no statistically significant differences (all >0.05). mSOFY anastomosis can be used as one of the safe and feasible reconstruction methods in laparoscopic proximal gastrectomy.