Central nervous system (CNS) idiopathic inflammatory demyelinating diseases (IDD) are mainly diseases caused by autoimmune factors that result in CNS demyelination damage and loss. It tends to accumulate in the brain, spinal cord and optic nerves. Multiple sclerosis (MS), clinically isolated syndrome (CIS), neuromyelitis optica spectrum disorder (NMOSD), myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) and acute disseminated encephalomyelitis (ADEM) are all common IDDs of the CNS. Besides, primary angiitis of the central nervous system (PACNS), autoimmune glial fibrillary acidic protein astrocytopathy (GFAP-A), etc. may also be included because they are important differential diagnoses. This study will establish a large prospective cohort study database of Chinese IDD, which will record detailed electronic information on IDD patients, including demographic and socioeconomic data, medical history, clinical information, medication, and relevant examination results. The long-term observational study will be used to understand the natural history of disease, disability progression rates, imaging and biological indicators, long-term treatment approaches and prognosis of Chinese patients with IDD, to find predictive markers for IDD progression and prognosis, and to identify factors that influence the treatment and prognosis of patients with IDD.