A child who is two and a half years old and can’t speak may be caused by abnormal growth and development, autism, or too little exposure to external language. 1. Abnormal growth and development: It may be due to the delayed development of hearing and vocal cords, or due to the child’s lack of intelligence. 2. Autism: It may be related to genetic and environmental factors. It is mainly manifested by different degrees of social interaction disorders, language development disorders, narrow interests and stereotyped behaviors, and most of the children are also accompanied by mental retardation. 3. too little contact with the outside world: if the child’s parents and family members are usually busy, seldom communicate and interact with the child, it may also affect the child’s language development. The child is two and a half years old does not speak, there may be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to determine the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.