Objective：To investigate the auxiliary application of dexmedetomidine hydrochloride in patients undergoing endoscopic nasal surgery under local anesthesia. Methods：A total of 60 patients of American Society of AnesthesiologyⅠ，Ⅱ undergoing elective endoscopic nasal surgery were randomly divided into two groups（30 cases in each group）：dexmedetomidine group（group D） and control group（group C）. 0.5 μg/kg dexmedetomidine was infused slowly for 10 min in patients of group D by intravenous pump be－fore operation，and then it was infused continuously until the end of the operation at velocity of 0.5 μg/（kg·h）. The same volume of saline was infused continuously until the end of the operation in control group. Endoscopic nasal surgery was completed under local anesthesia in both groups. Patients’ mean arterial pressure（MAP），heart rate（HR），saturation of pulse oxygen（SPO2），respiratory rate（RR），score of sedation or analgesia and adverse reactions were recorded in two groups at the following time points：before anesthesia（T0），operation beginning（T1），30 min during operation（T2），end of the operation（T3）. Results：HR，MAP，RR，visual analogue scale score，in group D were significantly lower than those in group C at T1，T2，T3（P<0.01） but Ramsay score in group D was significantly higher than that in group C at T1，T2，T3（P<0.01）. There was no difference in SPO2 at every time point in the two groups（P >0.05）. There was no significant difference in incidences of nausea，vomiting，respiratory inhibition in D group（P >0.05）. Conclusions：In－travenous administration of low dose of dexmedetomidine could relieve pain in patients undergoing endoscopic nasal surgery under local anesthesia，reduce fluctuation of hemodynamic and exert certain sedative effects without inhibiting respiratory inhibition，there－fore it is worthy of clinical application.