Nowadays, children's mental and physical growth and development are very fast. In today's society, children with advanced information can learn about sexual knowledge from various channels, and teachers and parents must pay attention to it. Grade 3-6 is a critical period for the development of primary school students, and their thoughts are still immature and they are in the stage of ignorance and curiosity. We should let them know about sexual knowledge and deal with the relationship with the opposite sex with a healthy attitude. After children enter junior high school, parents should pay more attention to the changes of children's behavior and thoughts. When children grow up, their secrets will increase with age, so parents should not avoid talking about sexual knowledge with their children. Sometimes children will try because they are unfamiliar, so they should communicate with their children and tell them that they know sexual knowledge, so as to protect themselves. At every stage of children's growth, they should be informed about physical health and mental health.