Homocysteine is associated with many diseases， and is also involved in the occurrence and development of mental disorders such as schizophrenia. The level of serum homocysteine in schizophrenic patients is elevated， but the specific mechanism is not yet clear. This article reviews the metabolic mechanism of homocysteine， the relationship between homocysteine and schizophrenia， and the mechanism behind its role in schizophrenia， in order to provide potential avenues for the treatment of schizophrenic patients.