Objective To investigate the influence of oral midazolam on postoperative behavioral changes(NPOBCs)in preschool children undergoing laparoscopic inguinal hernia sac ligation.Methods A total of 197 preschool children,118 males and 79 females,aged 1-6 years,BMI 14.0-24.5 kg/m2,ASA physical status Ⅰ or Ⅱ,who undergoing laparoscopic inguinal hernia sac ligation from July 2022 to A-pril 2023 were selected.The children were divided into two groups by random number table method:the oral midazolam group(group M,n=100)and the oral saline group(group C,n=97).In the observation room,group M received an oral dose of 0.5 mg/kg midazolam while group C received an oral dose of 5％sa-line 0.25 ml/kg before being accompanied by a clown doctor to the operating room after 30 minutes.Modi-fied Yale preoperative anxiety scale(m-YPAS)scores before entering the observation room and before ente-ring the operating room,as well as induction compliance checklist(ICC)scores before anesthesia induction were recorded.Postoperatively,FLACC and PAED scores were recorded at immediately,6,and 24 hours after surgery along with occurrences of postoperative nausea and vomiting and hypoxemia.Family members of the children were followed up at 1 day,7,14,and 30 days after discharge using PHBQ to record NPOBCs occurrence in children.Results Compared with group C,m-YPAS score,ICC score before anesthesia in-duction,PAED score immediately after surgery,and the incidence of NPOBCs 1 day,7,14,and 30 days after surgery were significantly reduced in group M(P＜0.05).There were no significant differences in YPAS scores before entering the observation room,6 and 24 hours PAED scores,incidence of postoperative nausea and vomiting,hypoxemia between the two groups.Conclusion Preoperative oral administration of midazolam to children undergoing laparoscopic inguinal hernia sac ligation can effectively alleviate periopera-tive anxiety and reduce the incidence of NPOBCs.It does not increase the risk of delayed awakening or post-operative adverse reactions in children.