Abstract: Objective：To investigate the effect of intranasal administration of different doses of dexmedetomidin on hemodynamics and postoperative behaviors of children undergoing tonsillectomy. Methods： 216 children undergoing tonsillectomy in the hospital were selected as the subjects. According to the dose of dexmedetomidine， they were divided into low-dose group and high-dose group. The hemodynamic changes in the two groups were observed after medication. The extubation time and the time of recovery from anesthesia were recorded. The degree of preoperative sedation， postoperative behaviors of children and pain were evaluated with the the Observer′s Assessment of Alertness/Sedation Scale(OAAS score)， the Pediatric Anesthesia Emergence Delirium(PEAD) and the modified Children′s Hospital of Easternontario Pain Scale(m-CHEOPS)， respectively. Adverse reactions during the perioperative period were statistically analyzed. Results： The MAP and HR of the two groups decreased firstly and then increased with the progress of the operation， and the SpO2 was relatively stable. Compared with T0， there were significant differences in MAP and HR of the low-dose group at the other time points after operation(P<0.05)， but there was no significant difference in SpO2(P>0.05). Compared with T0， there were significant differences in MAP of high-dose group at the other time points after operation and in HR at T3， T4 and T5(P<0.05)， but there was no significant difference in SpO2(P>0.05). The fluctuation ranges of MAP and HR in the high-dose group were significantly smaller than those in the low-dose group(P<0.05). The preoperative OAAS score of the high-dose group was significantly lower than that of the low-dose group [(3.2±0.6) vs(3.8±0.7)](P<0.05)， but there was no significant difference in extubation time or recovery time between two groups(P>0.05). The PEAD score and m-CHEOPS score of the low-dose group were significantly higher than those of the high-dose group [(13.7±4.3) and(4.5±0.8) vs.(12.4±4.3) and(3.4±4.3)](P<0.05). There was no significant difference in the total incidence of adverse reactions between the two groups(17.6% vs 16.7%)(P>0.05). Conclusion： The intranasal administration of high-dose dexmedetomidine is helpful to maintain the hemodynamic stability and avoid postoperative agitation in children undergoing tonsillectomy.