Objective: To investigate the efficacy of using selective cyclooxygenase-2 (COX-2) inhibitor parecoxib for postoperative analgesia of open liver surgery. Methods: Fifty-six patients undergoing open liver resection for cavernous hemangioma of the liver in Peking Union Medical College Hospital from September 2014 to December 2016 were enrolled and were randomly designated to control group and observation group, with 28 cases in each group. Patients in control group underwent patient-controlled analgesia (PCA), and those in observation group received PCA plus parecoxib treatment. The relevant perioperative variables, postoperative analgesic effects, recovery variables and adverse effects were compared between the two groups of patients. Results: There were no significant differences in preoperative data and intraoperative variables between the two groups of patients (all P>0.05). After operation, the blood ammonia levels and portal vein velocities showed no significant changes (both P>0.05) while the erythrocyte sedimentation rates and levels of high-sensitivity C-reactive protein were significantly increased in both groups after operation compared with their preoperative values (both P<0.05), but all these parameters showed no significance between the two groups (all P>0.05). The postoperative day (POD) 1 and 2 resting and exertion pain VAS scores, POD 3 resting pain VAS score and dose of analgesics used were all significantly reduced in observation group compared with control group (all P<0.05); the number of cases requiring additional pain relief was significantly decreased in observation group compared with control group (5 cases vs. 17 cases, P=0.001), and the incidence of postoperative vomiting was significantly decreased in observation group compared with control group (17.8% vs. 46.4%, P<0.05). No significant differences were noted in incidence of postoperative nausea, recovery variables and hospitalization costs between the two groups (all P>0.05). Conclusion: For postoperative analgesia of open liver surgery, combined use of parecoxib is safe and can effectively relieve pain and reduce the dose of opioids and the adverse effects, and meanwhile will not increase the hospitalization costs.