ABSTRACT Objective To explore the diagnostic value of pelvic ultrasound with single index and combined index for central precocious puberty.Methods 205 CPP girls were in the CPP group, and 221 healthy girls who underwent physical examination during the same period were selected as the control group. Perform pelvic ultrasound examination to compare the sizes of the uterus and ovaries of the two groups; select the high area under the curve (AUC) value and independent ultrasound index to establish a binary logistic regression model to obtain the combined ultrasound index Y, and compare the AUC values of the single index and the combined index. Results The uterine volume, ovarian volume, larger follicle diameter, number of follicles, and endometrial thickness in the CPP group were all increased to different degrees than those in the control group. The difference between the two groups was statistically significant (P<0.05). The ROC curve results showed that the AUC for the diagnosis of CPP by ovarian volume was 0.82 ml, cut-off value was 1.16 ml, specificity was 72.50%, and sensitivity was 82.20%; the AUC for the diagnosis of CPP by uterine volume was 0.79 ml, cut-off was 1.66 ml, specificity is 71.30%, and sensitivity is 61.20%. The combined ultrasound index Y combined with the formation of uterine volume, ovarian volume and endometrial thickness is more valuable in the diagnosis of central precocious puberty than a single ultrasound index (P＜0.05), with an AUC of 0.97, a cut-off value of 0.90, a specificity of 97.20%, a sensitivity of 85.19%. Conclusions The combined ultrasound index can further improve the diagnostic accuracy of pelvic ultrasound in children with central precocious puberty. KEYWORDS Pelvic ultrasound；Central precocious puberty；Logistic Regression