Objective To investigate the effects of ultrasound-guided quadratus lumborum block (QLB) on postoperative pain and quality of recovery (QoR) in patients after total hip arthroplasty (THA). Methods A total of 60 patients were enrolled for analysis, who underwent elective THA under general anesthesia in the Affiliated Hospital of Xuzhou Medical University from December 2018 to September 2019. They were randomized into control group (group C) and block group (group Q), with 30 in each group. Patients in group Q received QLB before general anesthesia, and those in group C did not. Both groups used patient-controlled intravenous analgesia pump after the operation. The visual analogue score (VAS) at rest and in movement were assessed postoperatively at 4,8, 24, and 48 h. The quality of recovery at postoperative 24 h was assessed using the quality of recovery questionnaire 15(QoR-15), and sleep quality on the first postoperative night was assessed using the Athens insomnia scale (AIS). The agition during awakening was assessed using the agition scores,the sedation at 10 min after extubation was assessed using the Ramsay sedation scale. The amount of general anesthetics, the number of postoperative salvage analgesia, adverse reactions and duration of hospital stay were documented. SPSS statistics 19.0 was used for data analysis. Results The VAS at rest at 4,8, and 24h were 1 (1,2), 2 (1,2) and 2 (1,3) for group Q and 3 (2,3),3 (2,4) and 3 (2,5) for group C, the difference being statistically significant (P＜0.05). The VAS in movement at 4,8, and 24h were 3 (2,4),3 (2,4) and 5 (4,6) for group Q and 6 (5,7),6 (5,8) and 7 (6,8) for group C, the difference being statistically significant (all P＜0.05). There was no significant difference in the VAS between the two groups at postoperative 48h (P＞0.05). The QoR-15 score at postoperative 24h in group Q was significantly higher than that in group C [(99.2±9.7) vs (74.4±9.1);P＜0.05], and the AIS on the first night after surgery in group Q was significantly lower than that in group C [(9.8±2.4) vs (16.0±3.6);P＜0.05]. The agitation score in group Q was significantly lower than that in group C [0(0,1) vs 2(1,2);P＜0.05]and the Ramsay sedation score at 10 minutes after extubation in group Q was significantly higher than that in group C [3(2,3)vs 1(1,1); P＜0.05]. The amount of remifentanil [(1.15±0.23) vs (1.73±0.26) mg] during surgery and the rate of salvage analgesia (23.3% vs 53.3%) in group Q were significantly lower than those in group C(all P＜0.05). There was no significant difference in the duration of hospital stay and the incidence of nausea and vomiting between the two groups (P＞0.05). Conclusion Ultrasound-guided QLB provides good postoperative analgesia for THA patients and improves early recovery.