The etiology of autism is still unclear, through clinical observation may be related to the following factors: 1, genetic factors, the role of genetic factors on autism has tended to be clear, but the specific mode of inheritance is not particularly clear; 2, perinatal factors, there are various complications in the perinatal period, such as birth injuries, intrauterine asphyxia, etc.; 3, immune system abnormalities, the number of T lymphocytes decreased, the number of helper T cells and B cells decreased, lack of suppression-induced T cells, reduced natural killer cell activity, etc.; 4. Neuroendocrine and neurotransmitter related to the dysfunction of various neuroendocrine and neurotransmitters. It was found that monoamine systems such as pentraxin and catecholamines are immature in autistic patients, and the pineal, subthalamic, pituitary, and adrenal axes are abnormal, resulting in increased 5-HT and endorphins and decreased secretion of adrenergic hormones.