Objective To explore the effect and predictive value of serum pentraxin-3 (PTX3) level on intravenous immunoglobulin (IVIG) resistance in children with Kawasaki disease (KD). Methods Children with KD diagnosed and treated from January 2017 to July 2022 were selected as the study objects. IVIG resistance was determined according to the IVIG treatment outcome. The relationship between PTX3 and IVIG resistance was analyzed by binary logistic regression. Receiver operating characteristic (ROC) curve was used to analyze the efficacy of PTX3 in predicting IVIG resistance. Results A total of 292 KD children (187 boys and 105 girls) with a median age of 25.0 (10.0-32.0) months were included, and 49 patients (16.8%) showed IVIG resistance. Binary logistic regression analysis showed that the independent risk factors of IVIG resistance were rash, cervical lymph node swelling, increased white blood cell count and CRP, decreased serum sodium, ALT≥33.2 IU/L, creatinine≥42.5 μmol/L, serum ferritin≥180.3 μg/L and PTX3≥19.3 ng/mL. The ROC curve showed that the area under the curve (AUC) of PTX3 for predicting IVIG resistance was 0.77 (95%CI: 0.68~0.85, P<0.001), with moderate accuracy. When the cut-off value was 21.5 ng/mL, the sensitivity, specificity, and Youden index for predicting IVIG resistance were 0.71, 0.69, and 0.40 respectively. Conclusions PTX3 is an independent risk factor for IVIG resistance in KD children, and has a good effect in predicting IVIG esistance.