Bone mineral density is an important indicator of bone nutrition. The bone mineral density of children gradually increases with age, and the accumulation of bone mineral density in adolescence increases significantly, which is the most sensitive period to affect the peak bone mass. Sex hormone promotes bone formation and bone mineral density acquisition, and the peak secretion of growth hormone and insulin-like growth factor-1 increases bone mineral density accumulation. Children with precocious puberty develop earlier, and the length of puberty is shortened, resulting in changes in bone mass accumulation. GnRHa(gonadotrophin releasing hormone analogue) treatment of precocious puberty also affects bone metabolism. The level of 25-(OH)D3 in children varies with age in a U-shaped curve, which is the lowest in adolescence. Changes in body composition such as bone mass in adolescence have a long-term impact on bone health and even adult physique.