The actual age that a person has from the day of birth is closely related to the bone age that the bones correspond to. The smaller the difference between the two, the more normal the child’s development. In order to determine a child’s growth and development, a bone age examination is necessary. Human bone development is basically similar, with each bone developing in a continuous and staged manner. Bones at different stages have different morphological characteristics, therefore, bone age examination can more accurately reflect the level of growth and development and maturity of an individual. It can not only determine the biological age of the child, but also through bone age early understanding of the child’s growth potential and the trend of sexual maturity: through the age of the bone can also predict the child’s adult height, the age of the bone examination is also a great help in the diagnosis of some pediatric endocrine diseases. So, at what age is it more appropriate to check the bone age of children? The best age for bone age examination is 3-15 years old. Bone age examination at different ages has different meanings, and it is recommended that two bone age examinations be conducted at the age of 4 weeks and 8 weeks. Bone age examination before 3-10 years old can detect growth and development diseases for early treatment according to the results, and at the same time, the prediction of height adopts reasonable dietary structure adjustment and changes in living habits to intervene in the final height. For girls, different ages of bone age correspond to different periods of height development. Bone age 11 to 13 years old, often in the height surge period, bone age 11 years old about the ninth month after the menarche, into puberty, and after the bone age of 17.3 years old, will stop growing taller. For boys, on the other hand, each stage occurs slightly later than for girls. Boys’ height increase occurs between 13 and 15 years of age, puberty occurs after 13 years of age, and height growth stops after 18.4 years of age.