Objective To explore the predictive value of pelvic ultrasound parameters for curative effect of gonadotropin-releasing hormone analog (GnRHa) in girls with idiopathic central precocious puberty (ICPP). Methods A total of 80 girls with ICPP treated in the hospital were retrospectively enrolled as study group between July 2022 and December 2023. All girls underwent pelvic ultrasound examination within 1d after admission, GnRHa treatment for 3 months, pelvic ultrasound re-examination and GnRHa stimulation test at 6 months after admission. The changes of hormones and pelvic ultrasound parameters before and after treatment were compared in study group. The correlation between pelvic ultrasound parameters and hormones was analyzed by Pearson correlation analysis. The predictive value of pelvic ultrasound parameters before treatment for curative effect in ICPP was analyzed by receiver operating characteristic (ROC) curves. Results? Before and after treatment, peak LH, peak FSH and peak LH/FSH in effective group were significantly lower than those in ineffective group (P<0.05), uterine long diameter, anteroposterior diameter, uterine volume, right and left ovarian volume were lower than those in ineffective group (P<0.05). Pearson correlation analysis showed that before treatment, uterine long diameter, anteroposterior diameter, uterine volume, right and left ovarian volume were positively correlated with peak LH and peak LH/FSH (P<0.05). Before treatment, uterine long diameter, anteroposterior diameter, uterine volume, right and left ovarian volume in effective group were lower than those in ineffective group (P<0.05). The area under ROC curve (AUC) of pelvic ultrasound parameters before treatment for predicting curative effect in ICPP girls was 0.903, showing high predictive efficiency. Conclusion? Pelvic ultrasound parameters have important predictive value for curative effect of GnRHa in ICPP, which can provide reliable clinical detection tools.