Abstract: Objective: To compare the preventive effects between dexmedetomidine and dezocine on shivering after spinal canal anesthesia.Methods: Ninety patients scheduled by unilateral knee replacement surgery under spinal canal anesthesia were randomly divided into the group D(using 0.5 μg/kg of dexmedetomidine),group Z(using 0.1 mg/kg of dezocine) and group C(using 0.9% of sodium chloride injection) (30 cases each group).All patients were anesthetized at L₂-L₃ using combined spinal and epidural anesthesia(CSEA).The drugs were pumped into after fixing anesthesia plane.The reaction and grading of shivering,oxygen saturation,nausea and vomiting were observed after the CSEA.The HR,MAP and Ramsay scores were recorded at the time of fixing anesthesia plane(T₀),end of drug injection(T₁),after 30 and 60 min of operation(T₂ and T₃) and end of operatiom(T₄).Results: The differences of the shivering classification,and incidence of nausea and vomiting among group D,Z and C were statistically significant(P<0.05).The HR in group D and Z at T₃ and T₄ were less than those in group C(P<0.01).The differences of the MAP at T₀ to T₄ among the 3 groups were not statistically significant(P>0.05).The sedative effects in group D at T₁ to T₄ were better than that in group Z and C(P<0.01),and no excessive sedation was identified.Conclusions: The dexmedetomidine can effectively decrease the incidence of shivering after CSEA,has good sedative effect,and does not increase the incidence of postoperative adverse reaction,which is suitable for clinical application.