Objective: To explore the application value of ultrasound in the differential diagnosis of idiopathic precocious puberty and the evaluation of curative effect of true precocious puberty in girls. Methods: 86 cases of girls with idiopathic precocious puberty who were admitted to our hospital from June 2016 to May 2019 were included in the study. According to the results of the gonadotropin-releasing hormone (GnRH) stimulation experiment, all the children were divided into the 52 cases with the true group (central precocity) and 34 cases with the sham group (peripheral precocity), and 30 healthy girls in the same period were selected as the control group. The results of uterine and ovarian ultrasound examination were compared in the three groups. In addition, the girls in the true group were treated with gonadotropin-releasing hormone analogue (GnRHa), and the results of uterine and ovarian ultrasound examination were compared before and 8 months after treatment. Results: The length diameter, transverse diameter, anteroposterior diameter and maximum follicular diameter of the true group were all larger than those of the sham group and the control group (all P<0.05). There was no statistical difference of the above indicators levels between the sham group and the control group (all P＞0.05). The length diameter, transverse diameter and anteroposterior diameter of the true group were all greater than those of the sham group and the control group, and the above indicators of the sham group were all greater than those of the control group (all P<0.05). After treatment, the length diameter, transverse diameter, anteroposteric diameter and maximum follicular diameter of the ovary in the true group were smaller than those before treatment (all P<0.05). After treatment, the length diameter, transverse diameter and anteroposterior diameter of the uterus of the true group were all smaller than those before treatment (all P< 0.05). Conclusion: Under ultrasound examination, the uterus and ovaries of idiopathic precocious puberty girls are significantly enlarged, and this feature is more obvious in true precocious puberty girls, which can assist to evaluate the therapeutic effect of true precocious puberty girls.