Abstract: Objective: To compare different doses of sufentanil in postoperative patient-controlled intravenous analgesia (PCIA)for patients with abdominal tumors. Methods: Eightypatients (ASA Ⅰ~Ⅱ) with abdominal tumors were divided into 4 groups with 20 patients each. Sufentanil was administered at 0.02, 0.03 and 0.04μg/kg·ml in group Ⅰ to Ⅲ, respectively, and fentanyl was administered at 0.3μg/ kg·ml in group Ⅳ. A 50mg / time dose of pethidine was added for patients with incomplete analgesia. The related data were recorded, e.g. the VAS value, Ramsay score, change in respiration rates and pulse oxygen saturation (SpO2) and the status of nausea and vomiting at 4, 24, 48 and 72 h after using the analgesia pump, as well as the daily volume of use for analgesia liquid and pethidine 3 days after surgery. Results: a). The VAS scores at each time point in group Ⅰ were obviously higher than that in the other groups (P<0.01); b). The Ramsay scores at 4 and 24 h after operation in group Ⅰ were lower than those in the other groups (P<0.05) and the scores at 48 and 72 h after operation in group Ⅲ were higher compared to the other groups (P<0.05). c). The incidence of nausea and vomiting was higher in group Ⅳ than in groups Ⅰ and Ⅱ (P<0.05), and the incidence of respiratory depression was higher compared to the other groups (P<0.05). d). The consumption of analgesia liquid 1 and 2 days after surgery and that of pethidine 1 day after surgery was significantly higher in group Ⅰ compared to that in other groups (P<0.01). Conclusion: Sufentanil is suitable for postoperative PCIA in patients with abdominal tumors, and a dose of 0.3μg/kg·ml has obtained good results. The dosage can be increased in a fewpatients but should be less than 0.4μg/kg·ml in general.