1, growth characteristics: children’s bones on the basis of relatively active growth, there are about two rapid growth period, one is since birth to 3 years old between; another in adolescence (generally girls in 11 ~ 13 years old, boys in 12 ~ 14 years old), in addition, children’s individual differences are also very different. 2, injury repair characteristics: (1) children’s bones have more organic matter, the younger the age, the greater the proportion of organic matter, so the elasticity and toughness of young children’s bones are greater, easy to deformation, encounter violence may be folded and continuous, cracking or green branch fracture. (2) The periosteum of children is thicker than that of adults, so it is not easy to rupture during general trauma, and usually remains connected on the side of the fracture, so children generally have less displacement after fracture, which helps to stabilize the reset. (3) Children’s bones are often injured in the growth mechanism (including bone energy, energy plate, periosteum and other structures), which is unique to childhood and the most important part of children’s bone injury. (4) Bone growth and shaping is closely related to the age of the child, and young children have a strong ability to compensate for and correct unsatisfactory alignment after fracture. (5) The growth and repair ability of bone is closely related to age. The younger the child is, the more immature the bone development is, and the more active its metabolic growth function is, and the greater the potential for repair once the injury occurs.