Objective:To analyze clinical characteristics of patients within 48 hours in pediatric intensive care unit（PICU）,and investigate causes and prognosis of extubation failure in reintubation children.Methods:A single-center retrospective study was conducted.Patients who were reintubated within 48 hours after extubation in PICU at Children's Hospital of Fudan University from January 1，2019 to December 31，2022 were retrospectively enrolled.Patients with unplanned extubation for various reasons which include re-intubation due to surgery and replacement of tracheal intubation were excluded.We analyzed the clinical characteristics，causes of extubation failure and prognosis.Main outcome measures included principal diagnosis，pediatric critical illness score（PCIS），the reason of intubation，the glasgow coma scale（GCS），the direct cause of reintubation，aeration time，hospitalization period，outcomes at PICU discharge and whether to extubate successfully.Results:During the study period，a total of 2 652 patients were extubated in PICU,and a total of 87 children were enrolled.Finally，63（72.4%）patients survived at PICU，nine（10.3%）patients died in hospital，and 15（17.2%）patients were discharged automatically.In the survival group，38（60.3%）patients were decannulated and 25（39.7%）patients underwent tracheotomy.The top three principal diagnosis in 87 cases were central nervous system disease[34（39.1%）cases]，lower airway disease[18（20.7%）cases] and sepsis[nine（10.3%）cases].Of the 87 children，28（32.2%）patients were reintubated due to central respiratory failure，21（24.1%）patients were reintubated due to lower airway disease，20（23.0%）patients were reintubated due to upper airway obstruction，14（16.1%）patients were reintubated due to cough weakness and/or swallowing disturbance，and four（4.6%）patients were reintubated for other reasons.In children with mechanical ventilation duration ≥7 days before first extubation，central nervous system diseases were the most common primary diseases，and it accounts for 55.6%.Central respiratory failure was the main direct cause of reintubation，accounting for 40.0%，and more patients(40.0%) had GCS scores＜8 before the first intubation.Compared with the successful decannulation group，the extubation failure group had the higher proportion of children with GCS＜8（32.7% vs.10.5%， P＜0.05），the longer median duration of mechanical ventilation before the first extubation[239（123，349）h vs.68.5（19，206）h， P＜0.05]and the longer median length of ICU stay[38（23，54）d vs.24（12，43）d， P＜0.05].After comparing the three groups including survival group，in-hospital death group and automatic discharge group，the PCIS score of the survival group was the highest，and the in-hospital death group was the lowest( P＜0.05). Conclusion:The rate of reintubation at 48 h after extubation in PICU is 3.3%.The immediate causes of reintubation mainly included central respiratory failure，lower airway disease，upper airway obstruction，cough weakness and/or dysphagia.The mortality rate of reintubation in critically ill children is high and the prognosis is poor.