【Abstract】 Objective To Observe the clinical effect of dexmedetomidine(Dex) combined with ropivacaine in epidural anesthesia for orthopedic surgery in elderly patients. Methods 60 elderly patients with ASAⅠ ~ Ⅱ grade under lower limb orthopedic surgery in our hospital in June 2012~December 2013 was slected and divided into two groups with random number method(n=30). The control group (group R) epidural injection 0.596% ropivacaine 15 ml + saline 1 ml, Dex group (group D) epidural injection 0.596% ropivacaine 15ml + dex 0.5 ug/kg (1ml). the two groups of sensory block onset time, sensory block ceiling plane, the highest plane of time, arrival time of T12, the duration of T12 block, motor block onset time and duration of motor block were comparised, and the two groups of patients the incidence of adverse events and postoperative conditions of POCD were compared. Results Compared with group R, the sensory and motor block onset time and duration of motor block were shortened, the duration of sensory block was prolonged in qroup D(P <0.05 or P <0.01); there was no difference in perioperative adverse reactions in two groups (P> 0.05), on 1d and 3d after surgery, the incidence of POCD in group D was lower than that in group R (P <0.05). Conclusion The efficacy of Dex combined with ropivacaine in epidural anesthesia for orthopedic surgery in elderly patients exceed the simple application of ropivacaine, and reduced the incidence of postoperative POCD.