Background: Profound trauma from laparoscopic-assisted gastrectomy (LAG) requires medication with a large number of opioids. The purpose of our study was to observe whether an incision-based rectus sheath block (IBRSB) based on the locations of the surgical incision could significantly reduce the consumption of remifentanil during LAG. Methods: A total of 76 patients were included. The patients were prospectively randomized into two groups. Patients in group IBRSB (n = 38) received ultrasound-guided IBRSB, and the patients received 0.4% ropivacaine 40–50 mL. Patients in group C (n = 38) received the same IBRSB with 40–50 mL normal saline. The following were recorded: the consumption of remifentanil and sufentanil during surgery, pain scores at rest and during conscious activity in the post-anesthesia care unit (PACU) and at 6, 12, 24, and 48 h after surgery, and use of the patient-controlled analgesia (PCA) at 24 and 48 h after surgery. Results: A total of 60 participants completed the trial. The consumption of remifentanil and sufentanil in group IBRSB were significantly lower than that in group C (p < 0.001). Pain scores at rest and during conscious activity in the PACU and at 6, 12, 24, and 48 h after surgery and patients’ PCA consumption within 48 h of surgery were significantly lower in group IBRSB than in group C (all p < 0.05). Conclusions: IBRSB based on incision multimodal anesthesia can effectively reduce the consumption of opioids during LAG, improving the postoperative analgesic effect and increasing patients’ satisfaction.