Objective To observe the effects of erector spinae plane block (ESPB) using ropivacaine combined with dexamethasone on the perioperative analgesia of patients during lumbar surgery. Methods According to the random number table method, 105 patients undergoing lumbar surgery under general anesthesia were divided into three groups (n=35): a ropivacaine+dexamethasone group (group RD), a ropivacaine+normal saline group (group R) and a control group (group C). Before anesthesia induction, group RD and group R were treated with 20 ml of 0.5% ropivacaine+2 ml dexamethasone (10 mg) and 20 ml of 0.5% ropivacaine+2 ml normal saline for bilateral ESPB, while no block was performed in group C. The intraoperative dosage of general anesthesia, postoperative Visual Analogue Scale (VAS) scores, the time of the first pressing analgesia pump, the dosage of sufentanil 48 h after operation, the ratio of effective pressing times of analgesia pump to actual pressing times (D1/D2), rescue analgesia rate and adverse reactions were recorded. Results The intraoperative general anesthetic dosage in group RD and group R were less than that in group C (P<0.05). The resting and turning VAS scores 2, 4, 8, 12 h and 24 h after operation in group RD and group R were lower than those in group C (P<0.05). The resting and turning VAS scores at 24 h and 48 h in group RD were lower than those in group R and group C (P<0.05). Compared with group R and group C, group RD presented remarkable increases in the time of the first pressing analgesia pump (P<0.05), decreases in the dosage of sufentanil 48 h after operation (P<0.05) and increases in D1/D2 (P<0.05), and decreases in rescue analgesia rate and the incidence of nausea and vomiting (P<0.05). Conclusions Ropivacaine combined with dexamethasone ESPB can provide good perioperative analgesia for patients undergoing lumbar surgery.