Abstract: OBJECTIVE To investigate the prevalence of health care-associated infections (HAIs) in pediatric intensive care unit (PICU) within three years and evaluate the direct economic burden so as to provide reference for effective prevention and control of HAIs. METHODS The medical data and information of HAIs were retrospectively collected from the children who were treated in PICU of a tertiary three-A hospital from 2022 to 2024. The prevalence of HAIs and changing trends were observed. The length of hospital stay and hospitalization costs were observed and compared between the HAIs group and the non-HAIs group by using 1∶1 propensity score matching (PSM). RESULTS A total of 3635 children were hospitalized in PICU for treatment during the three years， of whom 117 (127 case-times) had HAIs， with the incidence of HAIs 3.22% (the case-time infection rate 3.49%)， showing a downward trend year by year (χ²trend=4.076，P=0.044；χ²trend=4.343，P=0.037). The patients with lower respiratory tract infection (25.20%)， the patients with upper respiratory tract infections (18.11%) and the patients with bloodstream infections and urinary catheter-urinary tract infections (11.81%) ranked top 3 sites of HAIs. The HAIs mainly occurred during the 7th to 14th and more than 28 days after the admission to PICU. Staphylococcus aureus， Candida albicans and Acinetobacter baumannii were dominant among the pathogens causing HAIs. Totally 117 pairs of cases were matched successfully after PSM. The median length of hospital stay of the HAIs group was prolonged by 16 days as compared with the non-HAIs group(Z=-4.686，P＜0.001); the median of the total hospitalization costs increased by 7 287.80 yuan(Z=-7.234，P＜0.001). There was significant difference in the total hospitalization cost of the various age groups of children between the two groups(P＜0.05). CONCLUSIONS The incidence of HAIs shows a downward trend among the PICU children， however， the HAIs still prolong the length of hospital stay and aggravate the family economic burden.