Objective To evaluate the effect of a side hugging holding position combined with a self-made auxiliary device on venous blood collection procedure in outpatient children.Methods A convenience sample of children presenting to the outpatient venipuncture unit from November 2024 to June 2025 was enrolled.Participants were randomized by drawing lots into a control group (n=133) and an intervention group (n=132).The control group underwent venous blood collection using routine positioning and standard fixation methods.The intervention group underwent venous blood collection in a side hugging holding position combined with a self-made auxiliary device.The two groups were compared on procedural indicators (vascular filling status, time to complete blood collection procedure, first-attempt success rate), caregiver satisfaction, restraint stability score, and incidence of phlebotomy related adverse events.Results There were no statistically significant differences between groups in vascular filling status, first-attempt success rate, or incidence rate of phlebotomy related adverse events (all P＞0.05).The intervention group had significantly shorter blood collection procedure time, higher restraint stability scores, and higher caregiver satisfaction scores compared with the control group (all P＜0.05).Conclusion Using a side hugging holding position combined with an auxiliary device effectively stabilizes pediatric positioning for outpatient venous blood collection, shortens procedure time, and improves efficiency.