Objective To investigate the influence of dexmedetomidine on hemodynamic,cerebral state index(CSI) and awakening quality in elderly patients after total hip replacement.Methods Sixty cases of elderly patients undergoing total hip replacement surgery who ASA classification Ⅰ-Ⅱ,were divided into observation group and control group by random number table with 30 cases each.After establishing patients with upper limb venous access,the patients in observation group received load 0.4 μ g/ (kg· h) dexmedetomidine given by micro 10 min intravenous infusion pump,and the maintenance dose was 0.3 μ g/ (kg· h),while those in control group with pump equivalent in 0.9％ sodium chloride.Systolic blood pressure (SBP),diastolic blood pressure (DBP),heart rate (HR),CSI were recorded into the operating room (T0),beginning of pump drugs (T1),beginning of pump drugs 10 min(T2),beginning of skin incision (T3),beginning of skin incision 30 min (T4),extubation (T5),after extubation 30 min (T6).And recovery time,extubation time and observer's assessment of alterness/sedation (OAMS) score after surgery 30 min were recorded.Results The SBP,DBP,HR in two groups began to decrease at T2 and began to increase at T5,the difference was significant at T2-T5 and T0(P＜ 0.05).And the SBP,DBP,HR in observation group at T5 and T6 were lower than those in control group,the differences were significant (P ＜ 0.05).The CSI in observation group was began to decrease at T2 and began to increase at T5,the difference was significant at T2-T5 and T0 (P ＜ 0.05).And the CSI in observation group at T2-T6 compared with control group in the same period,the difference was statistically significant (70.34 ±4.99 vs.92.76 ±4.63,40.73 ± 3.79 vs.70.49 ± 3.51,40.93 ± 3.67 vs.71.82 ± 3.37,91.92 ± 5.28 vs.76.01 ± 4.90,92.49 ± 5.32 vs.80.53 ± 4.89,P ＜ 0.05).The recovery time and extubation time in observation group were lower than those in control group [(14.22 ± 1.11) min vs.(19.56 ± 1.05) min,(13.82 ± 0.94) min vs.(21.61 ± 0.88) min],and the OAA/S score was higher than that in control group [(4.29 ± 0.27) scores vs.(2.87 ± 0.24) scores],the difference was significant (P＜0.05).Conclusions The dexmedetomidine can reduce the impact on hemodynamics in elderly patients after total hip replacement,and can reduce CSI,deepen the depth of anesthesia,reduce the extubation time and recovery time.It is an ideal method of anesthesia for elderly patients after total hip replacement.