Abstract: Circular RNA (circRNA) is a widely present endogenous noncoding RNA that is covalently bonded at the 3' and 5' ends via trans-splicing to form a closed-loop structure with high stability, biological evolutionary conservatism, and tissue expression specificity. CircRNA has important biological functions, such as playing the role of microRNA (miRNA) sponge, regulating the expression of a parent gene, and improving transcription and translation levels. In gastrointestinal tumor, circRNA mainly plays the role of miRNA sponge, which affects the proliferation, differentiation, apoptosis, and invasion of cancer cells. In addition, circRNA was specifically expressed in the tumor, and the expression level significantly differs from that of paracancer. Therefore, a highly conserved and stable circRNA sequence is expected to be an early diagnosis and prognostic marker for gastrointestinal tumor. In this study, we review research advances on circRNA and its relationship with gastrointestinal cancers (esophageal, gastric, colorectal, and liver cancers).