Girls generally begin to enter puberty at the age of 11, but the determination of whether or not they have entered puberty is not determined by age, but is marked by the development of sexual organs and the appearance of secondary sexual characteristics. Puberty is the developmental stage of transition from childhood to adulthood. Generally speaking, the puberty period for girls ranges from 11 to 12 years old to 17 to 18 years old. But puberty cannot be judged solely by age. This is because there are relatively large individual differences in puberty, which are related to nutrition, region, diet, and so on. When a girl enters puberty, she enters a period of rapid growth in height, breasts begin to develop, menstruation occurs, pubic hair and armpit hair grow, and she begins to change her voice. Adolescent intelligence jumps forward, beginning to exercise life independently and participate in more complex social activities. Parents should pay attention to their children’s emotional changes and give them appropriate guidance.