Obsessive-compulsive disorder (OCD) is a chronic disabling mental illness with the core symptoms of obsession and compulsion, while its pathological mechanism has not yet been fully understood. In recent years, magnetic resonance (MR) technology has been used in the study of mental illness, because of its nonradiative and non-invasive advantage, etc. Many MR studies have found that OCD patients have cerebellar changes in structure and function, and these changes have contact with the incidence of OCD. This paper reviews the cerebellar’s role in the onset of OCD applying MR technology.