Precocious puberty is an abnormality of growth and development manifested by the early appearance of pubertal features. The incidence of this disease has increased significantly in recent years and has become one of the common pediatric endocrine disorders. It is more common in girls, with 4-5 times more incidence than in boys. In girls, breast development starts after the age of 10 and the first menstruation occurs at the age of 13-17 as normal; in boys, because puberty is 2 years later than in girls, the appearance of testicles, penis enlargement and other sexual characteristics at the age of 12 is normal. Generally, it is considered precocious for girls to start breast development before the age of 8 and menstruation before the age of 10; for boys to show sexual signs such as enlarged testicles and penis before the age of 9 is precocious. In girls, precocious puberty often begins with breast enlargement, which can be painful to touch. As the disease progresses, the breasts further increase in size and vaginal discharge increases, while the height growth of the affected child accelerates. If not treated properly, pubic hair, axillary hair and vaginal bleeding may occur later. The bleeding starts as irregular vaginal bleeding and gradually progresses to regular menstruation. The first sign of precocious puberty in boys is testicular enlargement, followed by penile thickening and growth, penile erection, and accelerated height growth. If not treated properly, pubic hair, beard, acne, voice change, and even sperm discharge may occur. The growth of height during puberty has a certain pattern. The period between the beginning of breast development and the first menstruation of girls is a period of rapid growth in height, and after the first menstruation, the period of slow growth, and generally after the first menstruation, the average height can only grow by 5-7cm. The best time for treatment. If you wait until after the onset of menstruation to start treatment, the improvement of the final height will be very limited. Likewise, boys who experience early testicular and penile enlargement and accelerated height growth should also come to the hospital in a timely manner. If they wait until they experience voice changes, throat nodes, beards, acne, or even sperm discharge before starting treatment, it will be too late to improve their height.