Schizophrenia, in medical terms, refers to the multiplicity of personality, which is what we usually call dual personality. Personality split is called "dissociative personality split" in scientific name; Its main feature is that patients separate their conscious activities or memories that cause their inner pain from the whole spiritual level to protect themselves, but they also lose the integrity of their identity. This kind of patient is not common in clinic, but common in drama. In the novel, split personality (dissociative disorder) can be divided into the following two categories:-psychological amnesia)-Multiple-personalityDisorders means that a person has two or more completely different personalities at the same time. The behavioral differences of these patients cannot be explained by the different behaviors of ordinary people in different occasions and roles. It seems that they are completely different people, and each personality has its own name, memory, characteristics and behavior. Usually, the original personality does not know the existence of another personality, while the new personality has a considerable understanding of the original personality. The characteristics of the new personality are usually quite different from the original personality, for example, the original personality is shy and depressed, while the new personality may be open and extroverted. Basically, according to my teacher's explanation, split personality is a very, very rare example. It has been about 100 years since the record of personality split, but there are few examples and there are some doubts about its correctness. At present, the treatment methods are uncertain, and there may be fusion, emotional therapy, hypnosis and so on. However, it is still uncertain whether it can be treated. Like The Fifth Sally or 24 Billion, these books are called true stories, but some authors add materials to make the novels wonderful. So what happened in the story is not entirely true. Personality split refers to "multiple personalities", which is called "dissociative recognition disorder" in the latest diagnostic classification of mental illness. This kind of patients will have two or more self-identity and personality states, and each self-identity and personality state has different cognition, relationship and ideas about the environment and self, and has patients' performance in different periods. Moreover, the patient's behavior can be completely controlled again and again, and some important personal data belonging to other personalities will not be remembered, not because of the influence of drugs or general medical conditions, nor because of childhood fantasies.