Low intelligence in children means that they have significantly lower intellectual functioning than most of their peers and have adaptive behavior deficits. Children with low intelligence usually have low memory, slow reactions, and even behaviors such as hitting and destroying objects. There are many causes of mental retardation in children, such as congenital mental retardation, acquired cranial brain injury or disease, malnutrition, endocrine disorders, etc. It is recommended that parents take their children to the hospital for diagnosis and treatment as soon as possible after the discovery of abnormalities, to avoid missing the best period of treatment. 1, congenital mental retardation: when the mother is pregnant, the surrounding environment is relatively poor or the fetus is born in the process of the accident may cause adverse effects on the growth and development of the fetus, so that the fetus is born with congenital mental retardation. Treatment of this condition of mental retardation of the child’s main means is rehabilitation training, although the effect is limited, but the future life of the child or a certain amount of help; 2, acquired craniosynostosis and injury: children if the cranial brain in the process of growth and development suffered mechanical damage or suffering from infectious, toxic diseases can also cause mental retardation of children. If this situation is caused by children’s mental retardation, need to actively treat the original disease, if the cranial brain injury repair after the child’s intelligence can not be restored to normal levels, or rehabilitation training to try to enhance the child’s intelligence; 3, malnutrition: children who do not consume enough essential nutrients in the process of growth, which will have a negative impact on the development of the child’s brain, resulting in children’s mental retardation. This situation should pay attention to the child in daily life to supplement balanced nutrition and with rehabilitation training; 4, endocrine diseases: such as hypothyroidism and other endocrine diseases can also cause children’s mental retardation, can go to the hospital to check the thyroid function, after diagnosis to actively treat the original disease, to avoid the original disease delayed healing leading to increasingly poor intelligence level.