Early detection of mental retardation in children is usually difficult because of their inability to speak. However, if the following signs of mental retardation in children are known, they can be detected early and can be helped. There are about 10 signs of mental retardation in children: ① Not smiling. The mentally retarded infant usually does not smile or only smiles at five destinations. (2) Blindness to sight and deafness to hearing. After 6 months of age, the infant is still unable to notice that adults are talking to him. Poor attention span and dull gaze. ③ Difficulty in feeding. The child often has nausea and vomiting when eating, poor chewing ability, and frequent choking and coughing. ④Wake tongue sticking, salivation, and even extended to 2-3 years old. (5) Delayed language development. 1 year old still cannot pronounce words purposefully. (6) Delayed motor development. 4 months old cannot lift their heads, 10 months old cannot sit alone, 12 months old cannot poke and pinch things with their hands, and when they start to walk, their feet move around. (7) They cannot distinguish between relatives and strangers. ⑧They do not cry immediately after stimulation, but only after a while or after repeated stimulation, and their cries are often shrill or weak. ⑨ Lack of interest in any surrounding environment, inattentiveness, and brief interest in toys. ⑩Many purposeless activities make it difficult for adults to understand. Although the causes of pediatric mental retardation are complex, most of them are related to the following factors: 1. genetic factors, such as parental mental retardation, parental inbreeding or parental anomalies, parents suffering from certain metabolic diseases, such as phenylketonuria, the paternal generation can pass on congenital mental defects to the offspring, resulting in pediatric mental retardation, if one parent is mentally retarded or both parents are mentally retarded, the children born to them The incidence of mental retardation is as high as 77-96%. 2, the mother’s gestational pathogenic factors: early pregnancy 8-12 weeks is the fetus in the mother’s brain formation and development of the critical period, a variety of physical and chemical toxins, public hazards, radiation, tobacco, alcohol, viral infections, are pathogenic factors that cause fetal brain dysplasia, followed by maternal abdominal trauma, drug abuse, mental and psychological stimulation, the fetus and the mother’s blood type is incomplete, can make the fetal development is impaired In addition, the fetal development can be impaired and the child can become mentally retarded. 3, the perinatal period of various factors, childbirth, prolonged labor, various causes of brain damage, ischemic hypoxic encephalopathy, can make the brain development is impaired and cause mental retardation. 4, infantile brain disorders or serious infections in other parts of the body can cause varying degrees of mental retardation. Mental retardation can be divided into mild, moderate and severe, generally mild patients can reach the level of 7-14 years old, moderate can reach the level of 3-6 years old, and severe less than 3 years old level.