Objective To investigate the safety and efficacy of remimazolam intranasal infusion for preoperative sedation in children. Methods A total of 150 children who underwent adenoidectomy or tonsillectomy under general anesthesia from August 2020 to March 2021 in our hospital were randomly divided into study group (B1 group, B2 group) and control group (C group), with 50 cases in each group. 30min before anesthesia induction, group B1 was intranasal injected with 0.1 mg·kg -1 of remimazolam, group B2 with 0.2 mg·kg-1 of remimazolam, and group C with normal saline. The nasal volume of each group was 5mL. Compare three groups of children with different time points of heart rate (HR), mean arterial pressure (MAP), blood oxygen saturation (SPO2) and sedative efficiency, anesthesia induction time, at the beginning of endotracheal intubation and surgical bispectral index (BIS), extubation time, recovery time, Psychometric Evaluation of the Pediatric Anesthesia Emergence Delirium Scale (PEAD) and postoperative adverse reactions occur. Results Compared with group C, MAP and HR of group B1 and B2 were decreased at 10min after nasal drip (P＜0.05) At the beginning of surgery and 30min after surgery, HR in group B2 was lower than that in group C (P＜0.05)SpO2 variation trend of the three groups was basically the same, indicating respiratory depression. The sedative efficacy were B2 group (96%) and group B1 group (86%) respectively which were significantly higher than that of control group(24%)(P＜0.05). During endotracheal intubation, BIS in groups B1 and B2 was lower than that in group C (P＜0.05). The time of anesthesia induction, extubation time and recovery time and PEAD score of 30 min after extubationin the study group were better than those in the control group (P＜ 0.05). There was no significant difference in the incidence of adverse reactions between the study group and the control group. Conclusion Remimazolam intranasal infusion is a safe, effective, convenient method for preoperative sedation of children. The sedative effect is definite, the vital signs are more stable, the incidence of adverse reactions is low, and the postoperative recovery is better