The causes of mental disorders can be analyzed in three aspects according to etiology: the first category is organic mental disorders, and these patients often suffer from damage to the brain organism, such as traumatic brain injury and brain hemorrhage due to car accidents, cerebral infarction, and brain atrophy. This type of disease is more difficult to treat, and only after the patient’s primary disease has improved, the mental symptoms can be controlled to some extent. The second type of pathogenesis is likely to be mental disorders caused by the use of psychoactive substances, such as alcohol, which are common. This is because psychoactive substances act on the neurotransmitters in the brain, causing neurotransmitter disorders in the brain and thus producing psychiatric symptoms. The treatment should first exclude the dependence and use of psychoactive substances, and then treat other psychiatric symptoms symptomatically. The third category of psychiatric disorders can be understood as primary psychiatric disorders, and often this category is functional, with common ones such as schizophrenia and anxiety disorders. These disorders require specific selection of medications to treat the patient’s symptoms. The common causes of primary psychiatric disorders can be formed by social factors and psychological factors in the individual patient, as well as factors that disrupt neurotransmitters in the patient’s brain.