To explore the occurrence and influencing factors of post-burn psychological stress disorder in preschool children. This study was a multi-center cross-sectional survey. From January 2022 to February 2023, 85 preschool children (aged 1 to 6 years) with burns admitted to the Affiliated Hospital of North Sichuan Medical College, Nanchong Central Hospital, Suining Central Hospital, Guang'an People's Hospital, and Guangyuan Central Hospital who met the inclusion criteria were selected as respondents. A self-made general information questionnaire was used to investigate the children's general data including gender, age group, residential area, main caregiver and their education level, and family type, as well as the injury condition including cause of injury and burn severity. The Child Stress Disorders Checklist was used to investigate the occurrence of psychological stress disorder in children at 3 days to 1 month after injury, and the incidence rate was calculated. The children were classified according to their general data and injury condition, and the occurrence of psychological stress disorder in children at 3 days to 1 month after injury was recorded, and the influencing factors for post-burn psychological stress disorder in preschool children were screened. A total of 85 questionnaires were distributed and 85 valid questionnaires were recovered, with an effective recovery rate of 100%. Among the children, there were 45 boys and 40 girls, with most children aged 1 to 3 years. There were slightly more children in rural areas than in cities. About half of the children were mainly cared for by their parents and grandparents, respectively, and the education level of the main caregivers was mainly high school/technical secondary school. The family type was mainly core family and extended family. The main cause of injury was hydrothermal scald, and the severity of burns was mainly moderate. The incidence rate of psychological stress disorder in this group of children at 3 days to 1 month after injury was 34.12% (29/85). There were statistically significant differences in the occurrence of psychological stress disorder in children with different age groups, causes of injuries, and burn severity at 3 days to 1 month after injury (with values​​of 9.18, 7.80, and 25.47, respectively, <0.05); there were no statistically significant differences in the occurrence of psychological stress disorder in children with different genders, residential area, main caregivers, main caregivers' education levels, or family types at 3 days to 1 month after injury (>0.05). Multivariate logistic regression analysis showed that age group and burn severity were independent influencing factors for the occurrence of psychological stress disorder in preschool children after burns (with odds ratios of 8.21 and 33.99, respectively, and 95% confidence intervals of 1.57-43.04 and 5.55-207.93, respectively, <0.05), the older the child and the more severe the burn, the higher the possibility of the occurrence of psychological stress disorder. The incidence rate of psychological stress disorder is high in preschool children after burns. Age group and burn severity are independent influencing factors for the occurrence of post-burn psychological stress disorder in this type of children.