BACKGROUND: Patients undergoing laparoscopic renal surgery often experience significant postoperative pain. Quadratus lumborum block (QLB) provides effective postoperative pain control after laparoscopic procedures, while lidocaine administered intravenously also exerts analgesic effects for surgical patients. We design this trial to compare the effects of i.v. lidocaine infusion with QLB on postoperative analgesia in patients undergoing laparoscopic renal surgery. METHODS: In this randomized noninferiority trial, a total of 120 adult patients undergoing laparoscopic renal surgery will be randomized to receive either i.v. lidocaine or unilateral QLB for postoperative pain management. Lidocaine will be i.v. administered at 1.5 mg/kg (ideal body weight) over 10 min during anesthesia induction, followed by an infusion of 1.5 mg/kg/h intraoperatively and in a post-anesthesia care unit. Ultrasound-guided anterior QLB with 0.375% ropivacaine 30 mL will be conducted before the start of surgery. Patient-controlled i.v. sufentanil will be used for pain relief during the first 48 h after surgery. The primary outcome is the cumulative sufentanil consumption during 0-24 h postoperatively, with a noninferiority margin of 5 μg. Secondary outcomes include pain intensity at rest and on coughing at 1, 6, 24, and 48 h postoperatively; sufentanil consumption within 24-48 h after surgery; rescue analgesic use within 0-48 h after surgery; nausea and vomiting within 0-48 h postoperatively; and quality of recovery at 24 and 48 h after surgery. DISCUSSION: The results of this trial will add to the clinical evidence for improving postoperative pain management in patients who undergo laparoscopic renal surgery. TRIAL REGISTRATION: Chinese Clinical Trial Registry (ChiCTR2400082974).