The critical period of growth and development for boys is generally puberty, between the ages of 11 and 18, when the reproductive system matures in its development and function. The first sex change is the genital testicles become larger, the penis becomes thicker and longer, the second sex characteristic is the emergence of pubic hair, the voice becomes thicker, the laryngeal knot protrudes, and gradually develops into a muscular, stout body, the voice is low manhood, these are mainly caused by the androgen secreted by the testicles increases. Spermatorrhea can also occur, etc. It is important to pay attention to pubertal hygiene.