What is the cause of crying. It is a negative reaction to the nature of emotions, and when things don’t go well, crying is used to give vent to the feelings. Some people, especially children, use crying to express a means of obtaining material things, such as what toys they need, what food they need, and by crying, parents will compromise and meet their demands. There is another kind of unclear expression, especially children use crying as a supplement to expression when verbal expressions and other expressions are not clear. There is also a kind of parent who is too strict, often intimidating and scolding the child, and the child will cry, using crying to express an emotion, which may also be a kind of resistance. There is another kind of family environment is relatively poor in all aspects, the child has a variety of dissatisfaction with the surrounding environment, so they cry to vent, express protest, etc.. Therefore, the reasons for crying are complex, especially in children, and need to be observed and handled with patience.