Objective To investigate the security and efficacy of dexmedetomidine inducing controlled hypotension in functional endoscopic sinus surgery。Methods Sixty patients subjected to general anesthesiawere were divided into 2 groups: the sodiumnitroprusside group(group N ), the dexmedetomidine group(group D )．The MAP was retained at 60-70 mmHg by sodiumnitroprusside or dexmedetomidine . Recorded the HR，MAP　before operation (T0), during operation (T1) and the time extubation (T2)．the time from the begining opration to the target hypotension，duration of operation and hypotension, extubation time，amount of bleeding and urine volum were recorded．Quality of the surgical field, the consciousness of patients and complications were assessed．Results There was no significant difference in age，weight，sex，duration of operation and hypotension during the two groups．The MAP was retained at 60 mm Hg -70 mm Hg in all patients. There was no significant difference in MAP, HR in the two groups at the T0. The time from the begining opration to the tatget hypotension was slower in group D (P<0.05) . The HR was significantly increased at T1 and T2 in group N, but slower in group D. Rebound hypertension occurred in group N when extubating. MAP was as same as the blood pressure before deliberate hypotension in group D, The quality of the surgical field was better in group D，while the extubation time was shorter in group N。The consciousness of patients was better in groupD. 6 patients felt frustrated after operation in group N。Amount of bleeding and urine volume is fewer in group N(P<0.05)．All patients did’nt occur postoperative complications just as respiratory depression。Conclusions Induced hypotension by dexmedetomidine is feasible and safe in the functional endoscopic sinus surgery．It shows good quality of the surgical field and fewer adverse reactions.