Schizophrenia is a very common psychiatric disorder. However, its etiology and pathogenesis is still unknown. Current theory saying that neurotransmitter imbalance such as serotonin or dopamine only provides limited effectiveness in schizophrenia treatment by drugs changing serotonin and dopamine concentration. Despite of such treatment, majority of schizophrenia patients still have very poor prognosis. Thus, the neurotransmitter imbalance theory is not correct. Here, I propose that schizophrenia is actually a TH2 dominant autoimmune disorder. The candidate of autoantigen could be acetylcholine receptors of CNS. My theory can explain the positive as well as negative symptoms of schizophrenia. By microarray analysis of PBMCS, one-tenth of the total 519 significantly expressed genes are immune-related genes. Among them, TH2 related genes are significantly up-regulated including IL-4, histidine decarboxylase, aldehyde dehydrogenase, CCR9, IgE Fc receptor, GATA2, serotonin receptor, phospholipase A2, and prostaglandin D2 synthase. Besides, TH1 and TH17 related genes are down-regulated including CXCL5, cathepsin C, and neutrophil related S100 binding proteins. The new theory sheds a light to better control this detrimental illness. Anti-inflammatory agents could be used to manage schizophrenia in the near future.