Objective To investigate the effect of erector spinae plane block (ESPB) with ropivacaine combined with dexamethasone on the incidence of postoperative pain in patients undergoing thoracoscopic surgery. Methods A total of 120 patients scheduled for elective thoracoscopic lobectomy were selected and randomly divided into two groups: Group A (ropivacaine plus dexamethasone) and Group B (ropivacaine), with 60 patients in each group. Group A received a single ESPB with 30 ml of 0.5% ropivacaine plus 5 mg of dexamethasone before surgery. Group B received a single ESPB with 30 ml of 0.5% ropivacaine before surgery. All patients underwent general anesthesia with endotracheal intubation during surgery, and patient-controlled intravenous analgesia (PCIA) was administered until 48 hours after surgery. The following indicators were recorded: incidence of chronic postsurgical pain (CPSP) and Visual Analogue Scale (VAS) scores at 3 and 6 months after surgery; area under the curve (AUC) of average VAS scores at rest and during coughing within 48 hours after surgery; duration of sensory block, time to first press of the analgesic pump, number of pump presses, and number of cases requiring additional tramadol for analgesia; duration of surgery, volume of fluid infusion, and blood loss; dosage of relevant intravenous anesthetics; use of additional vasoactive drugs; and incidence of adverse reactions such as dizziness and pruritus. Results Compared with Group B, Group A showed the following statistically significant differences (all P<0.05): Significantly lower incidence of CPSP and weaker pain intensity at 3 and 6 months after surgery. Significantly smaller AUC of average VAS scores at rest and during coughing within 48 hours after surgery. Significantly longer duration of sensory block and significantly delayed time to first press of the analgesic pump after surgery. Significantly fewer number of analgesic pump presses. Conclusions