Objective To investigate the effect of body position angle on gastric insufflation during the induction of general anesthesia in pediatric patients undergoing day surgery.Methods A total of 111 children scheduled for elective tracheal intubation under general anesthesia at the First Affiliated Hospital of Guangxi Medical University from December 2022 to March 2023 were selected as study subjects.Six children were ex-cluded due to unclear sonographic visualization of the gastric antrum,resulting in 105 children ultimately in-cluded in the study.The children were divided into three groups using a random number table method:Group D0(supine position),Group D5(5° head-up position),and Group D10(10° head-up position),with 35 children in each group.The presence of a"comet-tail artifact"on ultrasound was used as the criterion for determining gastric insufflation during anesthesia induction.The gastric antrum cross-sectional area(CSA)of the gastric antrum was measured before mask ventilation after loss of consciousness(T1)and immediately after tracheal intubation following mask ventilation(T2).The incidence of gastric insufflation,changes in CSA and their differences,and vital sign changes at T1 and T2,were compared among the three groups.Results Compared with Group D0,the incidence of gastric insufflation was significantly lower in Groups D5 and D10[25.7％(9/35)vs.20.0％(7/35)vs.54.0％(19/35)],and the difference was statistically significant(P＜0.05).Howev-er,there was no significant difference between Group D5 and Group D10(P＞0.05).No significant difference was observed in CSA at T1 among the three groups(P＞0.05).At T2,a statistically significant difference in CSA was found among the three groups(P＜0.05),with Group D10 showing a smaller CSA than Group D0(P＜0.05).The difference in CSA changes was statistically significant among the three groups(P＜0.05),with Groups D5 and D10 exhibiting smaller changes than Group D0,and Group D10 showing a smaller change than Group D5(P＜0.05).No significant differences were observed in mean artery pressure(MAP),heart rate,pulse oxygen saturation(SpO2)and pressure of end-tidal carbon dioxide(PETCO2)at T1 and T2 among the three groups(P＞0.05).A total of 6 children(5.7％)required brief adjustments in jaw support due to irregular PETCO2 waveforms or abnormal peak airway pressure.Conclusion In pediatric patients undergoing day sur-gery under general anesthesia,a 5° head-up position during induction significantly reduces the incidence of gas-tric insufflation and minimizes changes in gastric antral CSA,while a 10° head-up position does not provide ad-ditional benefits.