Ｏｂｊｅｃｔｉｖｅ　To evaluate the effect of sufentanil combined with ropivacaine by patient-controlled epidural analgesia (PCEA) for patients undergoing lower abdominal surgery.　Methods　One hundred and twenty ASA Ⅰ or Ⅱ patients, aged 28-66 years old, undergoing lower abdominal operation, were randomly divided into 3 groups (n=40): 0.5 mg/L sufentanil combined with 0.2% ropivacaine (group Ⅰ), 5 mg/L fentanyl combined with 0.2% ropivacaine (groupⅡ), and 0.2% ropivacaine (group Ⅲ). MAP, HR, VAS, and ramsay sedation score(RSS) were recorded at 4, 8, 16, 24, 48 h after the start of PCEA. The number of total presses of PCEA and side effects such as nausea, vomiting, pruritus, and respiratory depression were recorded at 48 h.　Results　There were no differences in age, sex, and weight among three groups (P>0.05). The VAS in group Ⅰ［(1.4±0.4), (1.6±0.5), (1.5±0.4), (1.6±0.3), (1.3±0.3)］ and group Ⅱ［(1.5±0.6), (1.6±0.4), (1.7±0.6), (1.5±0.4), (1.4±0.6)］ were significantly lower than that in group Ⅲ［(2.1±0.7), (2.4±0.6), (2.4±0.5), (2.3±0.7), (2.2±0.8)］(P<0.05) at each time point, respectively. The RSS in group Ⅰ［(2.4±0.6), (2.1±0.9), (2.4±0.5)］ was significantly higher than that in group Ⅱ［(1.4±0.7), (1.6±0.6), (1.6±0.4)］ and group Ⅲ ［(1.7±0.6), (1.4±0.3), (1.6±0.6)］ (P<0.05) at 8, 16, 24 h, respectively. The number of total presses of PCEA decreased significantly in group Ⅰ and group Ⅱ, compared with group Ⅲ (3, 4, 18, P<0.05), respectivey. The incidences of nausea and vomiting in group Ⅰ and group Ⅱ were significantly higher than that in group Ⅲ(15%, 12.5%, 0, P<0.05), respectively. There is no occurrence of respiratory depression in all groups.　Conclusions　0.5 mg/L sufentanil combined with 0.2% ropivacaine by PCEA was safe and effective for patients undergoing lower abdominal surgery.