Nonsuicidal self-injury (NSSI) refers to the direct, deliberate infliction of harm to one's body tissue without the intention to die. The prevalence of NSSI has increased significantly globally in recent years and has become an important public health problem affecting the health of people, especially adolescents. The occurrence of NSSI in adolescents is the result of the interaction of different factors. Many scholars have proposed various theoretical models to explain the mechanism of NSSI behavior based on previous research on the influencing factors of NSSI. Moreover, advances have been made in genetic and neuroimaging mechanisms related to NSSI. Understanding the genetic and neuroimaging mechanisms of NSSI is important for both describing and treating the disorder. This literature review discusses the progress made on the risk factors, theoretical models, and biological mechanisms of NSSI.