Objective: To investigate the application value of morning urine combined with pelvic ultrasound and Doppler uterine artery imaging in the preliminary diagnosis of central precocious puberty (CPP) in girls. Methods: A total of 96 precocious girls admitted to the Department of Pediatrics, Huaian Clinical College, Xuzhou Medical University from April 2022 to May 2023 were selected as the study objects. Age, weight, height and other data of the children were collected, serum basic luteinizing hormone (LH) and estradiol levels were examined, morning urine LH and follicle stimulating hormone (FSH) were collected, and bone age was detected. At the same time, pelvic Doppler ultrasonography was performed to evaluate the uterine artery pulse index (PI), uterine long diameter, transverse diameter, anteroposterior diameter, and uterine volume and ovarian volume. The girls were divided into non-CPP group and CPP group according to the results of GnRH stimulation test. Statistical software was used to analyze and integrate relevant data. Results: (1) The levels of morning urine LH, FSH and uterine length diameter in CPP group were significantly higher than those in non-CPP group, and the uterine artery PI was significantly lower than that in non-CPP group (P < 0.05). (2) Correlation analysis results showed that morning urine LH level was positively correlated with morning urine FSH, uterine long diameter, transverse diameter, anteriorposterior diameter, uterine volume, ovarian volume, serum LH peak and FSH peak (P < 0.05). Uterine artery PI was negatively correlated with morning urine LH, morning urine FSH, long diameter, transverse diameter, anterior and posterior diameter, uterine volume, ovarian volume, and serum LH peak value (P < 0.05), but had no significant correlation with serum FSH peak value (P > 0.05). Uterine length diameter was positively correlated with morning urine LH, morning urine FSH, transverse diameter, anterior and posterior diameter, uterine volume, ovarian volume and serum LH peak value (P < 0.05), but had no significant correlation with serum FSH peak value (P > 0.05). (3) The area under the curve (AUC), sensitivity and specificity of ROC curve analysis of morning urine LH, uterine artery PI, and uterine length diameter for diagnosing CPP in girls were 0.925, 91%, 84%; 0.915, 76%, 90%; 0.945, 95%, 88%, respectively. (4) When morning urine LH, uterine artery PI and uterine length were combined in the diagnosis of CPP in girls, the AUC, sensitivity and specificity were 0.974, 98% and 90.0%, respectively, which was better than single index. Conclusion: The combination of morning urine LH, uterine artery PI and uterine length diameter has the highest efficacy in the diagnosis of CPP in girls, and has the advantages of safety, non-invasive and convenient, which is suitable for clinical application.