Objective：This study aims to investigate the diagnostic value of morning urine combined with pelvic ultrasound and serum basal urinary gonadotropin(Gn)levels of girls with central precocious puberty(CPP). Methods：Total 83 girls with precocious puberty attending our hospital were enrolled in this study. The age，bone age，the uterus ultrasonic，basal serum Gn levels and other related informations were collected. For girls with suspected CPP，gonadotropin - releasing hormone(GnRH)stimulation test was performed. Then 83 girls were divided into CPP group and non -CPP group according to the results of GnRH test. At the same time， morning urine from all patients were also collected. Then，the Gn levels were detected by immunochemiluminometric assays. SPSS 25.0 software was used for statistical analysis of the data，and receiver operating characteristic curve(ROC)was drawn. Results：①The levels of luteinzing hormone(LH)and follicle-stimulating hormone(FSH)of morning urine in CPP group were significantly higher than those in non-CPP group(P ＜ 0.05). ②The LH levels in morning urinary were positively correlated with peak LH levels in the serum， uterine volume and ovarian volume(P ＜ 0.001)；urinary LH/FSH ratios were also positively correlated with peak LH/FSH ratios in the serum，uterine volume and ovarian volume(P ＜ 0.001). ③The area under ROC curve(AUC)，threshold，sensitivity and specificity of morning urine LH for diagnosis of CPP were 0.879，2.12 U/L，82.1% ，88.0% ，respectively；and AUC，threshold，sensitivity and specificity of uterine volume for diagnosis of CPP were 0.935，1.87 cm3 ，87.2%，88.0%，respectively；the sensitivity and specificity of serum basal LH(≥0.3 U/L)for CPP diagnosis were 89.7% and 80.0%，respectively. ④The AUC，sensitivity and specificity of the combination of morning urine LH，uterine volume and blood - based LH for diagnosis of CPP were 0.977，92.3% and 96.0% ， respectively. Conclusion：Morning urine LH combined with uterine volume and blood-based LH can be used as preliminary screening indicators for CPP in girls，which is non - invasive and convenient. These indicators can further improve the preliminary diagnostic efficacy of CPP，and have certain clinical application value.