Objective To synthesize and apply the best evidence of peripheral arterial catheter（PAC） placement in the pediatric intensive care unit（PICU）. Methods Utilizing the Joanna Briggs Institute（JBI） evidence-based nursing framework and the Ottawa Model of Research Use，ten pieces of best evidence were discerned and converted into twelve clinical audit criteria. A comparative analysis was performed the baseline phase and the post-implementation re-audit phase to evaluate nurses’ adherence to evidence，initial success rates of PAC insertion，and the occurrence of complications. Results During the post-implementation re-audit phase，total compliance with the 12 audit criteria markedly improved（48.24% vs. 80.22%，χ²=189.379，P<0.001）. Significant enhancements were noted in both the assessment and insertion domains（P<0.001），with seven critical indicators—evaluation of indications，coagulation status assessment，collateral circulation，operator qualifications，infection prevention，and pain management—demonstrating statistically significant increases（P<0.05）. The success rate of initial attempts dramatically increased（58.9% vs. 82.2%，χ²=10.899，P=0.001），while the occurrence of insertion-related problems greatly diminished（22.4% vs. 4.2%，χ²=11.208，P<0.001）. Conclusion The best evidence application of PAC insertion into nursing practice in the PICU can standardize nurses’ behavior，improve evidence adherence of nurses，and prevent procedure-related complications in critically ill pediatric patients.