Abstract: Circular RNAs (circRNAs) are a class of single-stranded non-coding RNAs that form circular conformations through non-canonical splicing or reverse splicing events. Recently, aberrant expression of circRNA has been observed in several cancers. An increasing number of studies suggested that circRNA is involved in tumor suppression or tumor promotion to varying degrees through diverse molecular mechanisms, highlighting its key role in the occurrence and development of tumors. In this review, we systematically summarize the latest research progress on the function and molecular mechanism of circRNA in malignant tumors of the digestive system. circRNA is expected to be further explored as a target molecule in the treatment of digestive system cancers in the future.