【Abstract】 Objective To observe the effects of parecoxib sodium on the post-operative pain relief elective decompressive lumbar laminectomy with posterior spinal fusion were randomly divided into three groups following intravenous administration of dosing schedule: Group A ( parecoxib I ) parecoxib 40 mg was injected during anesthesia induction; Group B (parecoxib II) parecoxib 40 mg was injected 10 min before the completion of sugrey; Group C ( placebo) the isochoric 0.9% physiological saline were injected either at anesthesia induction or 10 min before the completion of sugrey. All patients received the patient -controlled intravenous analgesia with morphine after surgery. The scores of visual analog scale (VAS), the total morphine consumption, and the opioid-related symptom distress were recorded at 2hr ,4hr ,6hr ,12hr ,24hr and 48hr after surgery. The red cell loss rate and the renal function in perioperative were measured, respectively. Results 1) The VAS scores of resting and coughing in group A significantly less than the group B and C at 5 minutes post-extubation and 2 hr after surgery (p<0.05), but it dose not show differences among the group B and C. The VAS scores were no statistically significance among three groups from 24hr to 48hr after surgery. 2）The total morphine consumption at 2hr,4hr,6hr,12hr were significantly reduced in the A and B groups compared with the control group (P < 0.05) .3）The total morphine consumption at 24hr and 48hr in the group A was significantly less than those in the B and C groups ( P < 0.05), but no statistically differences among the B and C groups . 4）The delay for first analgesic demand was increased obviously in the group A compared to the B and C groups (P < 0.05)，but no statistically significance between the B and C groups. Satisfaction with postoperative analgesia A and B groups were significantly better than the C group. 5）The red cell loss rate and the renal function in perioperative were no significant differences among the three groups. 6) The opioid-related symptom distress associated with opioid therapy were less in group A and B more than those in group C within 48hr after surgery. Conclusions Intravenous administration of the parecoxib sodium 40mg either at anesthesia induction or 10 min before the completion of surgery significantly decreased morphine consumption and side effects associated with opioid therapy, and did not affect the renal function compared with the control group. Administration of the parecoxib sodium at anesthesia induction rather than the completion of surgery showed more beneficial therapeutic effects on the patients with spinal fusion surgery.