【Abstract】Objective To investigate the effect of dexmedetomidine preconditioning on liver function in elderly patients undergoing Laparoscopic operation.Methods Eighty patients scheduled for laparoscopic cholecystectomy in treating cholecystolithiasis combine choledocholithiasis under interscaline brachial plexus block,were randomly divided into 2 groups(n=40 each):control group and dexmedtomidine group. Dexmedetomidine 1μg/kg was infused iv over 10 min before anesthesia induction．and then was infused at a rate of 0.5μg•kg-1•h-1 until 10 min before the end of operation. operation．Group control received the equal volume of normal saline. The plasma levels of IL-6 and MDA were detected before opertation(t0) 、at the end of the operation（t1）and d1（t2） and d3（t3）after operation..Results The plasma ALT、AST、IL-6 、MDA at t1-t2 were significantly increased compared to those at t0 in two groups（P<0.05)，the above Parameters d3(t3)after operation recovered to the levels before operation.the plasma concentrations of ALT、AST、IL-6 、MDA were lower in group dexmedetomidine than those at Group control(P<0.05). Conclusion Dexmedetomidine preconditioning may have the protective of liver function in elderly patients undering laparoscopic operation through inhibiting the oxidatiive stress responses.