1.Basic sex hormone measurement. Basal luteinizing hormone (LH) has screening significance, such as LH<0.1IU/L suggesting that there is no central puberty initiation, while LH>3.0-5.0IU/L can confirm that there is central puberty initiation (stimulation test is required if the diagnosis cannot be confirmed by the basal value). β-HCG and alpha-fetoprotein (AFP) should be included in the basic screening, which is an important clue for the diagnosis of HCG-secreting germ cell tumor. Elevated estrogen and testosterone levels are diagnostic adjuncts. 2. Gonadotropin-releasing hormone (GnRH) stimulation test. (Important basis for confirming the diagnosis of central precocious puberty) (1) Method: Intravenous injection of gonarelin 2.5μg/kg (maximum dose 100μg), measurement of serum LH and follicle stimulating hormone (FSH) levels before and 30, 60 and 90min after injection. (2) Judgment: Chemiluminescence measurement, if the peak excitation LH>3.3-5.0 IU/L is the threshold for determining true development, while the LH/FSH ratio>0.6 can be diagnosed as central precocious puberty. Currently, it is considered that a single excitation value of 30-60 min after excitation, meeting the above criteria, can also be diagnosed. If the peak excitation is dominated by elevated FSH and low LH/FSH ratio, it may be early stage of simple premature breast development or central precocious puberty, and the latter requires regular follow-up and rechecking of excitation test when necessary. 3. Utero-ovarian ultrasound. Unilateral ovarian volume ≥1-3 ml and multiple follicles ≥4 mm in diameter (newborns also have follicles, the key is to look at the size of the follicles, follicles over 4 mm in diameter are developing follicles), the ovaries can be considered to have entered pubertal development; uterine length >3.4-4 cm or uterine volume >2.5 ml can be considered to have entered pubertal development, endometrial shadow is visible suggesting estrogen is The endometrial shadow indicates a meaningful increase in estrogen. 4. Bone age. It is an important basis for predicting adult height. Bone age is crucial to determine whether menstruation is early and to predict whether adult height is short. 5. cranial pituitary MRI A cranial MRI (focusing on the saddle area pituitary gland) is required after the diagnosis of central precocious puberty (CPP), especially in the following cases: (1) All boys diagnosed with precocious puberty. (2) Girls with onset under 6 years of age. (3) Those with rapid sexual maturation process or other manifestations of central pathology (e.g., headache, dizziness, blurred vision, etc.). 6, other etiological screening: according to the specific clinical features and endocrine hormones after the initial screening for further endocrine examination, such as thyroid function examination to exclude hypothyroidism induced precocious puberty; as needed to do imaging examination of gonads, adrenal glands or other related organs, such as precocious puberty in boys more than 2/3 often can find the cause, in addition to the above examination, but also need to perform ultrasound examination of testes, adrenal glands, abdominal cavity and other organs to exclude Tumors, etc.