The clinical manifestations of mental retardation in children are various, and can be analyzed from several aspects: firstly, the manifestations are in speech and thinking, which may include delayed development of speech or slurred speech, and after the age of 7, the children can communicate less with others, that is, there are certain obstacles in communication or pronunciation. In terms of thinking, they may have poorer thinking ability or slower thinking, and may lack the ability to make abstract generalizations. For some severe mental retardation, loss of language ability or loss of thinking ability is also more common. Secondly, in terms of perception, some of the senses may be slow or the range of perception may be narrow, and it is difficult to distinguish the size, shape and color of some objects. In terms of attention and memory, children with developmental delay often have poor concentration and memory loss. Emotionally, children with developmental delays tend to be childish or immature, lack self-control, and are prone to impulsivity. In addition, the character is timid, or more withdrawn, more shy, this is a more common aspect. There is also mental retardation, mainly in the motor and behavioral aspects, sometimes motor incoordination, that is, the body’s dexterity is relatively poor, some can also be manifested as hyperactivity, that is, too active, and some have destructive or aggressive behaviors, which is also considered to be a manifestation of mental retardation.