Circular RNA (circRNA) is a type of functional RNA characterized by a covalently closed continuous loop. CircRNA is generated by pre-mRNA through back splicing and plays an essential role in epigenetic gene expression at transcription and post-transcription levels. In recent years, more and more studies have found that circRNA are involved in occurrence and development of liver diseases, and have the potential to become biomarkers for the diagnosis and treatment of liver diseases. This article summarized the classification, formation, biological functions and roles of circRNA in different liver diseases.