Primary language disorders are due to dysfunction of articulatory organs, such as shortening of the tongue muscle band, cleft lip and palate, and uncoordinated laryngeal muscles. The first is hearing impairment. Hearing is an important channel for language perception, and when children with hearing impairment, whether conductive or sensory-neural, are unable to correctly detect sound transmission, producing varying degrees of language development impairment. The second is mental retardation, which is the most common cause of language disorders. The language development process in this type of child follows the order of a normal child, but its development is slower than normal, for example, in Down syndrome. The third autism, language disorders in children with autism are manifested by a complete lack of understanding, no language or overly stereotyped language, almost no eye contact, and limited facial expressions and postures. The fourth is behavioral disorders. There is a close relationship between language disorders and behavioral problems, and the two can be causal. In terms of causes, apparent emotional trauma or psychosocial adverse factors can affect children’s language development and can cause language development disorders, such as selective mutism, a rare language disorder that usually has an onset at age five, where the child does not speak in specific situations, such as school.