Objective To investigate the clinical effect of intramuscular dextromethorphan and tramadol premedication for postoperative analgesia.Methods 60 cases of ASA Ⅰ～Ⅱ underwent surgical procedures of extremitas inferior were divided into 3 groups randomly.Patients in every group were provided with dextromethorphan 20mg,tramadol 2mg/kg and normal sodium 4ml(control group) respectively.All patients received PCEA analgesia postoperatively.The postoperative visual analogue scale(VAS),ramay score,consumption of paregonic and adverse reactions were observed.Results After operation,VAS score in group of dextromethorphan was lower than that in control group significantly(P