Abstract: Objective: To investigate the application value of the biphasic hemodynamic changes of dexmedetomidine(DEX) in elderly patients during general anesthesia induction.Methods: Fifty general anesthesia elderly patients with ASAⅠto Ⅱ were randomly divided into the DEX group(group D) and saline group(group C)(25 cases each group).Before general anesthesia,the group D were injected with 0.5 μg/kg of DEX(20 mL) for 10 mins,and then with 0.3 μg·kg^-1·h^-1 for 5 mins after intubation,the group C were injected with the same volume saline.The mean arterial pressure(MAP) and heart rate(HR) in two groups were recorded after entering the operation room(T₀),the end of DEX load(T₁),before tracheal intubation(T₂) and after 1,3 and 5 mins of intubation(T₃,T₄ and T₅).Results: Compared with T₀,the MAP in two groups from T₂ to T₅ decreased significantly(P<0.05 to P<0.01).The differences of the MAP in group D between T₁,T₂,T₄,T₅ and T₃ were not statistically significant(P>0.05),the differences of the MAP in group C between T₁,T₂ and T₃ were statistically significant(P<0.01),and the MAP in group D at T₂ was higher than that in group C(P<0.05).Among group D,the HR at T₁,T₂,T₄ and T₅ were obviously lower than that at T₀,the HR at T₂,T₄ and T₅ were significantly lower than that at T₃(P<0.01).The HR in group C at T₄ and T₅ were lower than that at T₀(P<0.05),the HR in group D at T₁,T₂ and T₅ were significantly lower than that in group C(P<0.01).Conclusions: The application of DEX during the general anesthesia induction can increase the arterial blood pressure,inhibit the blood pressure decreasing resulted from the anesthesia,reduce the heart rate and response of tracheal intubation and stable cardiovascular function.