Precocious puberty is defined as the onset of secondary sexual characteristics in girls before the age of 8 years and in boys before the age of 9 years. Central precocious puberty (CPP) refers to the development of internal and external genitalia and secondary sexual characteristics due to the premature secretion of gonadotropin-releasing hormone (GnRH) by the hypothalamus, which activates the gonadal axis and causes the pituitary gland to secrete gonadotropins, resulting in the development of gonads. The etiology of central precocious puberty is divided into two main categories: (1) organic lesions of the central nervous system. (2) Idiopathic CPP (ICPP) in which no organic pathology is found. In girls, ICPP is more common, accounting for more than 90% of CPP; in boys, on the contrary, more than 80% are organic. Diagnostic basis 1. Early appearance of secondary sexual characteristics: girls before 8 years of age, boys before 9 years of age. 2, gonadotropin-releasing hormone (GnRH) stimulation test: luteinizing hormone (LH) stimulation peak, girls > 12IU/L, boys > 25IU/L, LH peak / FSH peak > 0.6 ~ 1.0. GnRH stimulation test method: GnRH 100μg/m2 or 2.5 ~ 3.0μg/kg intravenous injection, at 0min, 30min, 60min and 90min respectively to collect blood. The blood samples were collected at 0min, 30min, 60min and 90min to measure the serum FSH and LH concentration. 3. Enlarged gonads: In girls, ovarian volume >1ml and multiple follicles >4mm in diameter were seen under ultrasound; in boys, testicular volume >4ml and progressive enlargement with prolongation of the disease. 4. Accelerated linear growth. 5.Bone age exceeds age by 1 year or more. 6.Serum sex hormone level increases to the level of puberty. Among the above diagnostic bases, 1, 2 and 3 are the most important and necessary. However, if the duration of the disease is very short at the time of consultation, the GnRH excitation value may sometimes not reach the above diagnostic values, as well as the ovarian size. Such cases should be followed up and, if necessary, the above tests should be repeated in a few months. In girls, linear growth acceleration during puberty usually occurs about six months after breast development, but there are also late cases, even about 5% of them present one year before menarche or in the year of menarche. In boys, the growth acceleration occurs 1 year before the change of voice. In children with short duration of disease and slow developmental progress, the bone age may not be obvious, while peripheral precocious puberty may also show bone age; the same is true for elevated sex hormones, which cannot distinguish between central and peripheral precocious puberty. Therefore, the diagnosis of CPP should be based on a combination of all data. In all boys with confirmed CPP and girls under 6 years of age, or those with rapid maturation and suspected saddle area tumors, MRI or CT should be performed to detect the lesion. Differential diagnosis GnRH stimulation test is basically able to differentiate central precocious puberty from peripheral precocious puberty. It is worth noting that PICPP can be converted into CPP without clinical signs of precocious puberty, so close follow-up is needed and the test should be repeated if necessary.