The etiology and pathogenesis of ADHD in children are still unknown. The current research has some associations in genetics, brain anatomy, neurobiochemical neurophysiology, psychosocial factors and other aspects. 1, genetic factors: the onset of ADHD in children has long been found to have a familial tendency. Early studies have shown that this family aggregation is related to genetics. The prevalence of ADHD in children is higher in first- and second-degree relatives with ADHD. A controlled study of children with ADHD and normal children found that parents of children with ADHD had more history of ADHD in childhood and that siblings of children with ADHD had a prevalence several times higher than controls. 2, minor brain injury: Patients with brain injury, especially frontal lobe injury, can develop attention deficit, hyperactivity and other behavioral abnormalities. Therefore, it has been speculated that ADHD may be due to minor brain injury or disease. However, in recent years, many scholars have confirmed through some rigorous case-control studies that the proportion of children with this disease who have significant brain injury and central nervous abnormalities is not high. 3. Neurobiochemistry: mainly there is an imbalance between dopamine and norepinephrine. Animal experiments as well as studies in humans suggest from different perspectives that children with ADHD have abnormal catecholamine pathways mainly in the brain. Measurements of epinephrine and dopamine concentrations in urine, blood and cerebrospinal fluid support the hypothesis that dopamine and epinephrine renewal is reduced. Cerebrospinal fluid measurements in children with ADHD showed either decreased dopamine renewal or increased dopamine sensitivity, validating the dopamine hypothesis of ADHD. Neuropsychological, pharmacological and brain imaging studies have shown that the dopamine and noradrenergic neurotransmitter systems of the frontal lobe and striatal loop are involved in the pathophysiological process of the disease. Another study found that blood flow was reduced in the striatum and periventricular posterior injection in children with either attention deficit disorder with ADHD or with other neuropsychiatric symptoms; in contrast, blood flow in the major sensory and sensorimotor areas increased in relative perfusion. It has been shown that after the application of Ritalin, the perfusion to the basal ganglia and midbrain increases, while the perfusion to the anterior cortex decreases, especially in the motor areas of the cerebral cortex. Therefore, it has been speculated that the mechanism of ADHD may be related to the altered distribution of cerebral blood flow, but the exact conclusion is to be further confirmed. 5, sensory integration dysfunction: The so-called “sensory integration dysfunction” refers to the brain’s inability to adequately process sensory information from all parts of the body. Because the integration of the senses in the brain (processing and finishing), just like too little food, the body is not adequately nourished, insufficient sensory or sensory integration in the brain is not good, the brain will also occur “malnutrition”, poor organization of all aspects of the body’s activities, resulting in inattention, hyperactivity and other abnormal phenomena. The reason for the dysfunction of sensory integration in children with ADHD is that: the tall buildings in the city deprive children of the opportunity to get in touch with greenery; parents hold their children in their arms for a long time so that they lack the activities needed for growth such as practicing head lifting and rolling on the ground; some mothers require caesarean sections to give birth to their children in order to keep their bodies in shape, which deprives children of the only opportunity to get tactile training through the birth canal. These reasons make the child not get enough movement, the brain also did not get the corresponding sensory information stimulation and poor development, they appear attention deficit, too much movement and poor self-control and other symptoms. 6. Delayed development: Clinical observation shows that children with ADHD often have clumsy fine collaborative movements, inability to discriminate between left and right, difficulty in visual and auditory transitions, abnormal spatial location awareness, and other neurological soft signs. Epidemiological studies have found that children with ADHD often have delayed speech, delayed language development, abnormal speech function, stuttering, functional enuresis and other delayed problems. 7. Environmental, social and family factors: negative social climate and peer influence, economic reasons, overcrowded housing, unstable family structure, parental discord or divorce, maternal depression, physical or psychological abuse of the child by family members, lack of attention to the child’s needs, and inappropriate family education methods.