【Abstract】 Objective To evaluate the influence of different intravenous infusion with dexmedetomidine (Dex) on the recovery process of patients undergoing thyroid surgery with general anesthesia. Methods Ninety ASA status I-II patients，aged 20-59 years，scheduled for elective thyroid surgery were randomized into 3 groups: Dex single dose intravenous infusion group (Dex 0.5 μg/kg in 10 min, followed by normal saline, n=30, Group D1), Dex continuous intravenous infusion group (Dex 0.5 µg•kg-1•h-1, n=30, Group D2) and control group (Group C). After induction with fentanyl, propofol and rocuronium, all patients were performed tracheal intubation and mechanical ventilation. Anesthesia was maintained with sevoflurane inhalation until the end of the operation, fentanyl and cisatracurium were given at 40 min intervals until 30 min before the end of the operation. Patients in the 3 groups were all started infusion at 10 min before the operation and discontinued at 30 min before the end of the operation. During the operation the concentration of sevoflurane was varied to maintain mean arterial pressure (MAP) within ±25% of the preinduction values and the bispectral index (BIS) within 45±10. The operative consumption of sevoflurane，the dosage of Dex, fentanyl and cisatracurium were observed. MAP, heart rate (HR), pulse oximetry (SpO2) and BIS were recorded at the time-points of before induction (T0), terminal of operation (T1), before extubation (T2), immediately extubation (T3), 1, 3, 5, 10, 15, 30, 45 min after extubation (T4-T10). The recovery time from the end of the operation to spontaneous breath, eye opening, extubation and orientation were also recorded. The incidences of adverse effects, visual analogue scale (VAS) scores and Ramsay sedation scores at 30 min after extubation，preoperative and postoperative cognitive function by using mini-mental state examination (MMSE) were assessed. Results Compared with T0, values of MAP and HR increased statistically at T2 -T5 in Group C (P<0.05). Compared with Group C, values of MAP at T1-T4, T6-T8 and HR at T3- T6 decreased statistically in Group D1 and D2 (P<0.05). The consumption of sevoflurane, the agitation incidence and level, the incidence of high blood pressure and tachycardia，VAS scores of Group D1 and D2 were all significantly lower than those of Group C(P<0.05). The bradycardia incidence of Group D1 were significantly higher than those of Group D2 and C (P<0.05). There were no significant differences in recovery time, Ramsay scores, MMSE scores among the 3 groups (P>0.05). Conclusion Dex intravenous infusion in patients undergoing thyroid surgery with general anesthesia can keep stable perioperative hemodynamics, relieve cough reflex, agitation incidence and level，while did not prolong recovery time and affect postoperative cognitive function. Its continuous intravenous infusion is an optimal choice than its single dose intravenous infusion.