Abstract: Objective：To explore the effect of patient-controlled intravenous analgesia (PCIA) using oxycodone combined with sufentanil on cesarean section patients.Methods： Sixty elective cesarean section patients were randomly divided into two groups: SF group (sufentanil 100 μg and ramosetron 0.3 mg), OS group (sufentanil 50 μg, oxycodone 50 mg, and ramosetron 0.3 mg). All patients were received combined spinal-epidural anesthesia, and applied with PCIA after surgery. Making 0.9% sodium chloride solution to 100 mL, continuous dosage 1 mL/h, pulse dosage 2 mL, the time was 10 min. Numerical pain scores of somatalgia at rest(NRS-R) or movment(NRS-M), numerical pain scores of uterine contraction(NRS-U) , patient-controlled intravenous analgesia doses, and side effects were assessed at 6 h,12 h and 24 h after the operation. Results： At the time points of 6,12 and 24 h after surgery, the scores of NRS-M, NRS-R, and NRS-U in OS group were lower than those in SF group. Times of bolus and accumulated drugs consumption in OS group were less than those in SF group (P<0.05).The incidence of nausea in SF group was higher than that in OS group (P<0.05). There was no significant difference in the incidences of vomiting, dizziness, pruritus or respiratory depression between the two groups. Conclusions： Oxycodone combination with sufentanil in patient-controlled intravenous analgesia may be more effective and without increasing side effects compared with sufentanil alone after cesarean section.