Objective: To compare the clinical effects of postoperative patient controlled epidural analgesia (PCEA) with different combinations of tramadol and/or buprenorphine. Method:The 150 cases of surgical patients were ran domly divided into 6 groups: 0.6% tramadol (group T_1). mixture of 0.6% tramadol and 0.15% bupivacaine (group T_2), mixture of 0.0015% buprenorphine and bupivacaine (group B_1) , mixture of 0. 0015% buprenorphine, bupivacaine and 0.6% tramadol(group B_2). 0.15% bupivacaine(group C_1), 0.0015% buprenorphine(group C_2). With a Graseby- 9300 PCA pump in the loading-continuous-PCA model, the doses were 5mL-0.5ml-1ml respectively. Result: (1)In the first postoperative 24 hours the amount of drugs used in each group was similar; (2)1n these six groups, both visual analog scale scores and the ratios of tatol deliveries to demands were B_2