Twelve-year-old boy long beard can be caused by normal growth and development, can also be caused by precocious puberty, need to specific problems, specific analysis. Usually the general puberty of boys from 12-14 years old, if the boy before the age of nine years old children appear secondary sexual characteristics is defined as precocious puberty. Boys generally have a fixed order of development, the first is the increase in testicular volume, with the increase in testicular volume, scrotal skin color darkening, the penis began to grow, thickening, the emergence of pubic hair and armpit hair growth, hair color gradually become darker, thicker. Finally the voice begins to appear low and grows a beard. It takes 4-5 years from the start of development to grow a beard, although there are individual differences. Since the child’s beard appears early, we need to carefully recall the exact time when the child’s testicles enlarged. If it is before the age of 9, it is precocious puberty, so we need to take the child to the doctor to check the bone age, etc. If it is after the age of 9, and the child does not have any other discomforts, we can continue to observe the child.