Abstract: Objective To analyze the incidence of blood oxygen saturation(SpO₂) decrease influencing factors during the intra-hospital transport of pediatric critically ill children by using a prospective cross-sectional survey, and provide a reference for clinical optimization of the intra-hospital transport plan for critically ill children. Methods Two hundred and four critically ill children who met the research conditions in Hangzhou First People's Hospital Affiliated to Medical School of Zhejiang University from September 2019 to November 2019 were selected as the study subjects. They were divided into observation group and control group. An investigation scheme was developed for various factors that may affect SpO₂ reduction during the transportation of children. All possible influencing factors were recorded and analyzed statistically. Results (1) The incidence of SpO₂ decrease was 60.29% in the process of intra-hospital transport of critical children, and the time of SpO₂ decrease was mainly within 5 minutes of the beginning of the transfer;(2) The factors that may affect the decrease of SpO₂ during the transport in critically ill children were: age, body mass index(BMI), basic disease, pediatric early warning score(PEWS), blood pressure, respiratory rate, age of transfer nurse, assistance of attending doctor in the process of transfer, transfer path, transfer distance, accident in the process of transfer, transfer time(P<0.05);(3) Risk factors of SpO₂ decrease during the intra-hospital transportation of critically ill children: multivariate logistic analysis showed that the risk factors of SpO₂ reduction decrease during the intra-hospital transportation of critically ill children were the low age( 0-6 years old), respiratory and/or nervous system diseases, one or more items in PEWS score is 3 points, the experience of the transfer nurse was less than 3 years, transportation path, transportation process accidents the high risk factors of SpO₂ reduction intra-hospital transport of critically ill children. Conclusion The incidence of SpO₂ decrease is high during the intra-hospital transportation of critically ill children. The main risk factors are the serious condition of the children, the low efficiency of the transportation process and the improper protective measures. The optimization of the transportation process, the strengthening of the training of the transportation personnel and the careful assessment of the risk of intra-hospital transportation of critically ill children, raise the transportation efficiency and the protective effect, and can improve the safety of the critically ill children.