At present, people are very interested in bone age and find it very mysterious, and we often meet normal children who come to ask for a bone age check in our daily outpatient clinics. In fact, bone age is formed after X-ray irradiation, which is radioactive, so it is generally not necessary to do a bone age check if it is normal. The following is a little bit of information about bone age. Wrist bone X-ray standard technical requirements: take the left wrist positive position. The left hand is placed in the center of the dark box, the center of the bulb is facing the 3rd metacarpal bone, the 5 fingers are naturally separated, the thumb and the palm at an angle of 30 °, the 3rd finger and the arm into a straight line. In addition to casting all the wrist bones, it also includes the radial-ulnar trunk 3-4 cm, and the distance between the tube pieces is 85 cm. Carpal bones (8 pieces in total): capitate, hook bone, triangular bone, lunate, navicular bone, large polygonal bone, small polygonal bone, and pea bone. The significance of bone age evaluation: Bone age only indicates the maturity of the epiphyseal bone center, which is an independent growth indicator, not dependent on age and growth rate changes. Bone age is consistent with physical and sexual development and can be used as an important indicator of maturity. Generally, the age of bone reaches 12 years old as the mark of entering puberty. Dynamic observation of bone age changes is important for evaluating the growth trend of individuals and the efficacy of pediatric endocrine diseases. Bone age assessment methods: simple counting method, chart method, scoring method and computerized bone age scoring system. The most commonly used are G-P atlas bone age assessment method and TW2 bone age assessment method.B-P method of height prediction: this method was proposed in 1946, and revised in 1952 in accordance with the G-P bone age atlas, which can better meet the clinical needs. Adult height prediction = (height at that time/P)×100(cm).P value according to the developmental rate of bone age is categorized into normal (G-P bone age within age ± 1 year), early (G-P bone age > age + 1 year), delayed (G-P bone age < age - 1 year), P value can be according to the G-P bone age lookup table.