Objective To investigate the feasibility of dexmedetomidine administered locally for lumbar plexus combined with sciatic nerve block in the elderly patients undergoing hip fracture surgery. Methods Sixty patients (ASAⅡ－Ⅲ) undergoing elective hip fractures surgery in the First Center Hospital of Baoding were randomly assigned into group R (0.4%ropivacaine 50ml for lumbar plexus and sciatic nerve blocks) and group RD (0.4% ropivacaine 50ml containing dexmedetomidine 0.5μg/kg for lumbar plexus and sciatic nerve blocks). The onset time of sensory and motor block, durations of sensory and motor block and duration of analgesia, mean arterial blood pressure (MAP), heart rate (HR) and SpO₂, and occurrences of adverse reactions, such as nausea and vomiting, nerve injury and poisoning of local anesthetic were observed and recorded. SPSS statistics 17.0 was used to analyze the data. Results Compared with group R, the durations of sensory and motor block, and analgesia were significantly longer in group RD (all P<0.05). At 15,30, 45,60 and 90min after administration, the MAP were obviously decreased and HR were remarkably lower in group RD than the corresponding basic values and those in group R (all P<0.05). However, there were no adverse reactions such as hypotension, bradycardia, hypoxemia, nausea and vomiting, nerve injury and local anesthetic poisoning in both groups. Conclusion Dexmedetomidine of 0.5μg/kg combined with ropivacaine for lumbar plexus and sciatic nerve blocks can significantly prolong the duration of block and analgesia, without increasing the incidence of adverse reactions such as bradycardia and hypotension, and can be safely and effectively used for the anesthesia of hip fracture surgery in elderly patients.