OBJECTIVE：To observe the effects of dexmedetomidine on hemodynamics of patients underwent cardiac valve replacement in the anesthesia induction. METHODS：92 patients underwent cardiac valve replacement were randomly divided into observation group and control group，with 46 patients in each group. Both groups received routine anesthesia induction regimen of midazolam 1-2 mg/kg+ fentanyl 0.05 mg/kg+ propofol 1-2 mg/kg+ cis-atracurium 0.15 mg/kg. Observation group was additionally given dexmedetomidine 0.5 μg/kg，within 10 min with pumps，and then maintained with 0.4 μg/（kg·h）till the end of operation； control group was additionally given constant volume of normal saline with pumps. SBP，DBP，MAP，HR，cardiac output（CO）， cardiac index（CI），stroke volume（SV），stroke volume variation（SVV）before anesthesia induction（T0），5 min after medication （T1），2 min after anesthesia induction（T2），1 min after intubation（T3），3 min after intubation（T4）and 5 min after intubation （T5）were recorded in 2 groups as well as OAA/S at T0 and 5 min after pumping dexmedetomidine（T1）. ADR of 2 groups during anesthesia was also recorded. RESULTS：There was no significantly difference in SVV of 2 groups at T0-T5 （P＞0.05）；SBP， DBP，MAP，HR，CO，CI and SV of observation group at T0-T5 were all better than those of control group，with statistical significance（ P＜0.01）；there was no statistically significant difference in OAA/S of 2 groups at T0（P＞0.05），and OAA/S of observation group at T1 was decreased significantly and lower than control group，with statistical significance（P<0.01）. There was no statistically significant difference in the incidence of ADR as cardiac arrhythmia and hypotension between 2 groups（P＞0.05）. CONCLUSIONS： Dexmedetomidine can reduce the influence of anesthesia on the hemodynamics of patients underwent cardiac valve replacement with good safety.