Babies who do not speak and understand everything may be related to language delay, motor aphasia, autism and so on. Normal babies can understand and can simply say some words at the age of 1. If the baby still can not speak at 18 months, disease factors need to be considered and analyzed as follows. 1. delayed language development: babies will use body language to communicate in addition to not talking and not rejecting socializing with others, which may be caused by delayed language development. 2. Motor aphasia: the baby can understand what others say, but there is a problem with language expression, and he/she will have difficulty in speaking and speak late. 3. Autism: If the child understands everything, but does not speak, and is not willing to socialize, and the mental behavior may be abnormal, this situation needs to pay attention to whether it is autism. It is recommended to take the baby to the hospital in time to check, usually to communicate with the child more, to help the child to speak.