Objective To systematically evaluate effectiveness, dosage and adverse reaction of sufentanil versus fentanyl for postoperative patient-controlled epidural analgesia (PCEA), so as to provide evidence for rational drug use in clinic. Methods Databases including The Cochrane Library, the special trials registered in the Cochrane anesthesia group, MEDLINE, EMbase, CBM, CNKI, VIP and WanFang Data were searched by the end of 2012, and the relevant periodicals were also manually searched to collect the randomized controlled trials (RCTs) on sufentanil versus fentanyl for postoperative patient-controlled epidural analgesia. According to the Cochrane Handbook 5.0, literature was screened, data were extracted, and quality of the included studies was critically assessed. Then meta-analysis was performed using RevMan 5.1 software. Results A total of 25 RCTs involving 1 944 patients were included. The results of meta-analyses showed that: a) as for visual analog scale (VAS), compared with the fentanyl group, the postoperative VAS at 2-hour, 4-hour, 8-hour, 12-hour, 24-hour and 48-hour was decreased in the sufentanil group; b) as for sedation scale, the fentanyl group, the postoperative sedation at 12-hour and 24-hour was lower in the sufentanil group when adopting 0 to 3 points scoring method, but there were no significant differences at other time points; c) as for drug dosage, compared with the fentanyl group, the postoperative drug consumption at 24-hour and 48-hour was less in the sufentanil group; d) as for adverse reaction, the incidence of postoperative nausea, vomiting, dizziness and somnolence in the sufentanil group was lower than those in the fentanyl group. But there was no significant difference in other adverse reactions such as skin itching, limbs numbness and motor disturbance between the two groups; and e) as for the demands of additional analgesic drugs, compared with the fentanyl group, the incidence of demanding additional analgesic drugs was lower in the sufentanil group. Conclusion Compared with fentanyl, sufentanil has better effects of analgesia and sedation for PCEA; Its dosage and incidence of adverse reactions are lower, so sufentanil is safer in clinic.