Infant mental retardation is mainly detected through delayed neuromotor development. Early manifestations of infant mental retardation include not being able to feed, not being able to cry and smile, delayed development of large movements, and not being able to understand parental instructions. 1. Can’t breastfeed: Sucking reflex and swallowing reflex are innate, if the child can’t suck or spit out the milk when breastfeeding, and often drool, it is likely to indicate that there are problems with their intelligence, and that they can’t either suck or swallow. 2. Won’t cry and smile: 1~3 months old babies can express their needs through crying and can also communicate with their parents through smiling. If the baby is around three or four months old and still can’t smile or cry it is likely that there is a problem with brain development. 3. delayed development of large movements: if the baby to four or five months of age can not roll over, seven or eight months of age can not hold things to sit up, two or three years of age will not be able to stand, this is likely because of brain development problems, resulting in delayed development of large movements. 4. Can’t understand parents’ instructions: 10~12 months old babies can make corresponding actions according to some simple instructions from parents, if the children still can’t do actions according to the instructions or can’t emit sounds to imitate their parents, it may also be low brain development. If the baby has the above performance, it is recommended to go to the regular hospital for examination, clear diagnosis, and timely treatment.