This prospective, randomized controlled clinical trial aims to evaluate whether remimazolam can reduce the incidence of postoperative delirium (POD) in elderly patients undergoing laparoscopic radical gastrectomy for gastric cancer. A total of 170 patients aged 65 years or older will be enrolled and randomized in a 1:1 ratio to receive either remimazolam or a propofol-midazolam regimen for anesthesia induction and maintenance. Standard perioperative monitoring, BIS-guided anesthesia depth control, and postoperative pain management will be applied in both groups. The primary outcome is the incidence of postoperative delirium within 5 days after surgery, assessed twice daily using the 3D-CAM. Secondary outcomes include emergence agitation, extubation time, postoperative pain scores, cognitive function at discharge, intraoperative hemodynamic stability, unplanned ICU admission, postoperative complications, and length of ICU stay. This study aims to determine whether remimazolam provides a safer and more effective anesthetic option for improving postoperative neurological outcomes and recovery in elderly patients undergoing laparoscopic radical gastrectomy.