Childhood aggression has been studied for nearly a century, but there is still no uniform definition. A more authoritative definition of childhood aggression is that it is behavior that is intentionally hurtful and not permitted by social norms, including physical aggression such as intentional hitting, kicking, pushing, and pinching, and verbal aggression such as coaxing nicknames and slander. Aggression is the most common behavioral problem in children and can occur in infancy and early childhood, with the highest frequency in preschool and decreasing with age thereafter. Professor Dodge, an American psychologist, classifies aggression into two types: “reactive aggression” and “proactive aggression” according to its cause. The former is triggered by the individual’s perception of hostile provocation from others, a defensive response to external threatening stimuli, mainly manifested as anger, temper tantrums or loss of control, while the latter is an effective way for individuals to achieve their goals, such as through coercion, control, intimidation of peers to achieve their goals. If the behavior is reactive aggression, the specific situation at the time needs to be analyzed, and it cannot be simply assumed that it is caused by the child’s own problems. If children often have active aggressive behavior, parents need to pay great attention to this situation can also be divided into two categories of factors: the child itself and external factors. 1, the child itself factors (1) age factors: small age infants and toddlers if there are some occasional aggressive behavior, you need to consider whether they have physical discomfort, is not hungry or sleepy? Need to change diapers? Or sick with a cold? In these states of somatic discomfort, infants and toddlers’ irritability will increase, and their lack of verbal expression makes them more likely to express various discomforts through aggressive behaviors. (2) Developmental disorders: Many developmental disorders such as autism spectrum disorder and mental retardation can lead to increased aggressive behavior due to the characteristics of the disorders themselves, and in addition to more aggressive behavior, these children also have many other developmental problems, such as later language and motor development than normal children of the same age, poor social skills and verbal communication skills, and more other behavioral problems. (3) Other developmental and behavioral problems (3) Other developmental and behavioral problems: Some children with behavioral deviations may show more aggressive behaviors, such as children with ADHD or a history of brain injury, and these children may have more active aggressive behaviors. Some ordinary people seem insignificant events, may cause them more violent reactive aggressive behavior. 2, social and environmental factors American psychologist Bandura has done a famous psychological experiment on children’s aggression, the results suggest that children’s aggression is the result of learning, is through personal interaction with the environment, through observation, imitation of the behavior of others and obtained. For preschool children, the main factors include family, peers and mass media. (1) Family factors: Parent-child relationship is one of the most important factors affecting children’s social and emotional development. Family members who express anger and even aggression to each other for a long time will significantly increase the level of reactive and proactive aggression. Moreover, children imitate and learn aggressive behaviors from family members’ conflicts and treat others with such aggressive behaviors, thus forming a vicious circle. (2) Mass media factors: Children are now spending more and more time with cell phones, tablets, and television, and the violent content in the media has a subtle influence on children, and children lack the ability to distinguish right from wrong and are prone to blindly follow suit. Some studies have shown that long hours of television viewing and a preference for cartoons such as beat-em-ups are risk factors for aggressive behavior in preschoolers. Therefore, it is worthwhile for parents and society as a whole to think about how to help children choose TV programs and give them the right guidance.