The onset of regressive autism is generally a slow process in which the child gradually forgets acquired skills over a period of weeks to months; however, about 1/3 of children with regressive autism have sudden onset episodes, with deterioration of acquired skills occurring within 1-2 weeks or a few days. These sudden regressive episodes are often related to the child’s physical illness, epilepsy, or physical or psychological trauma. The onset of the disease is slowly followed by a reluctance to interact with others, confinement to a hermetically sealed environment, isolation from human interaction, sudden loss of language and social skills, mood swings, and gradual deterioration of intellectual and language functions. If a child is diagnosed with regressive autism, there is little chance of recovery, but he or she can undergo autism rehabilitation in a professional institution to train self-care and speech and behavior skills, and to restore daily social interaction to some extent. In daily life, parents should not ignore the social needs of children, they need to accompany children more often, try to speak in a calm tone, and take children to participate in group activities more often, so that children can feel happy and cared for, which can effectively prevent the emergence of regressive autism.