Abstract: Objective： To observe the effect of different doses of dexmedetomidine preoperative intranasal medication in children adenoidectomy. Methods： 60 children for adenoidectomy（ASA Ⅰ or Ⅱ） were randomly divided into three groups(n=20 each)： the D1，D2 and NS groups.Group D1 was given dexmedetomidine 1 μg·kg-1， group D2 was given dexmedetomidine 2 μg·kg-1 and group NS was given normal saline 0.5 mL. HR and SpO2 were monitored and recorded before intranasal medication(T1)， 15 min(T2)， 30 min(T3)， 45 min(T4) after intranasal medication. The children′s sleep latency was observed. At 45 minutes（T4） after medication， the scores of sedation， mood and behaviour at separation from parents were evaluated were recorded. Results： HR in group D2 at T3 and T4 were lower than those in group NS(P<0.05). Compared with group D1，HR at T4 were lower in group D2(P<0.05) .There were no significant differences（P>0.05） in SpO2 between the three groups. The children′s sleep latency in group D2 was (26.5±5.7)min，which was shorter than that in group D1 (33.8±4.3)min(P<0.05). The sedation scores and mood scores in group D1 and D2 were higher than those in group NS(P<0.05). The scores of behaviour at separation from parents in group D2 were better than those in group NS(P<0.05). Compared with group D1， the scores of sedation， mood and behaviour at separation from parents in group D2 were significantly higher (P<0.05).Conclusion： Premedication with intranasal dexmedetomidine 2 μg·kg-1 in pediatric patients undergoing adenoidectomy is safe， and has good sedation effect， which may be used as a choice for children premedication.