The etiology of stuttering is unknown, and may be related to genetic, developmental, neurophysiological, and psychiatric factors, as follows: First, genetic factors. Although no specific genes related to stuttering have been found to exist, many family members of people who stutter also have symptoms of stuttering. Secondly, developmental factors. Children aged 2-3 years old have a rapidly expanding vocabulary, but their speech function is not yet skillful, they are not good at choosing words, and their speech is often hesitant, repetitive and non-fluent, which may gradually disappear before the age of 4. Third, neurophysiological factors, some stuttering children’s brain activity in a certain area, or organizational structure is different from that of normal speakers, which may interfere with the transmission of information between the brain and the muscles that control vocalization. Fourth, mental factors. Stuttering can be caused by intimidation, being forced to speak, sudden mental stimulation, environmental changes, parental separation or death.