Ｏｂｊｅｃｔｉｖｅ　To investigate the effects of dexmedetomidine(Dex) on baroreflex sensitivit(BRS) of rabbits，and evaluate the effects of Dex on the tension of vagus nerve. Methods Twenty four healthy male rabbits were randomly divided into 3 groups(n=8), including group C(control), group D1(low dose of Dex), and group D2(high dose of Dex). Rabbits were administered with Dex normal saline in group C, they were administered with Dex at loading dose of 10 μg/kg, and then pumped with Dex at 5 μg·kg-1·h-1 in group D1, they were administered with Dex at loading dose of 60 μg/kg and then at 30 μg·kg-1·h-1 in group D2. The values of BRS was measured before(T0), 30 min after(T1) and 60 min after(T2) intravenous pumping of Dex.　Results　The values of BRS at T1, T2 in group D1 and D2 incareased compared with T0(P＜0.05), The values of BRS at T2 in group D1 decreased significantly compared with T1(P＜0.05). The values of BRS in group D1 and D2 were significantly increased than group C at T1, T2(P＜0.05). The values of BRS in group D2 were significantly increased than group D1 at T1, T2(P＜0.05).　Conclusions　Dex can increase BRS of rabbits, with increasing of Dex concentration of BRS increased effect are more significant and persistent, also which reflects the Dex can increase the vagus nerve tension in dose-dependent manner.