First of all, it has humanitarian value, so I won't go into details here. Secondly, learning from the education of severely mentally retarded children can improve our understanding of the education of moderately and mildly mentally retarded children and even normal children. Understanding and studying these special groups may also contribute to the development of psychology and medicine. Thirdly, children with severe mental retardation are not only recipients, but also givers in special ways. They can show the purest and most extreme state of human nature, so that we still have the opportunity to face ourselves and some profound questions, such as what is life, what is love, what is giving, what is happiness and what is "valuable". In working with children with severe mental retardation, a person's growth is immeasurable.