Ｏｂｊｅｃｔｉｖｅ　To investigate the effect of continuous intravenous infusion of different doses of dexmedetomidine（Dex） on the intraoperative hemodynamics and recovery period for orthopedic surgery under general anesthesia， to explore appropriate dose and method of intravenous infusion of Dex.　Methods　One hundred ASAⅠ-Ⅱpatients （weight 50 kg-75 kg） undergoing elective orthopedic surgery were randomly divided into four groups： group D1， group D2， group D3 and group C. The patients in group D1， group D2 and group D3 were all treated with a continuous intravenous drip of 0.6 μg/kg Dex 10 min before the induction of general anesthesia， and followed by a continuous intravenous drip of 0.2， 0.4 μg·kg-1·h-1 or 0.8 μg·kg-1·h-1 Dex， respectively. The patients in group C were treated with the same amount of normal saline. The admistration of Dex was stopped 30 min before the end of surgery. Patients in the four groups were treated with same method of anesthesia. The amount of propofol was adjustted based on bispectral index（BIS）， which was the indicator of the depth of sedation， to maintain anesthesia. The changes of hemodynamic parameters at the time premedication， 1 min before and after tracheal intubation， insion， 1 min before and after tracheal extubation， the consumption of propofol， postoperative recovery time to eyes opening， extubation and orientation， and the incidence of agitation， nausea and vomiting， respiratory depression and somnolence were recorded.　Results　The heart rate （HR） of the time 1 min after tracheal intubation and extubation was lower than that in group C（P<0.01） . The systolic blood pressure（SBP） and diastolic blood pressure（DBP） at the time 1 min after tracheal intubation， insion and 1 min after extubation were all lower than that in group C（P<0.05）. Under the same sedation conditions， consumption of propofol in group C， D1， D2， D3 was 1 180， 1 095， 822， 696 mg， respectively. Dex reduced the consumption of propofol in a dose-dependent manner（P<0.05）. The difference of recovery time to eyes opening， extubation and orientation in the four groups was not statistically significant（P>0.05）. The incidence of postoperative agitation， nausea and vomiting and respiratory depression in group D1， group D2 and group D3 was significantly lower than that in group C（P<0.05）. But the incidence of somnolence in group D3 was higher compared with group C（P<0.05）.　Conclusions　Intraoperative continuous intravenous infusion of 0.2 μg·kg-1·h-1-0.4 μg·kg-1·h-1 Dex may effectively maintain stable hemodynamics of patients undergoing orthopedic surgery during general anesthesia， prevent the cardiovascular reactions of tracheal intubation， insion and tracheal extubation， reduce propofol requirement and postoperative adverse reactions， improve the patients outcomes.