Circular RNA(circRNA)is a new type of non-coding RNA molecule with covalent closed-loop structure.CircRNA is involved in various processes of tumor development,such as tumor angiogenesis,epithe-lial-mesenchymal transformation(EMT),drug resistance,invasion,etc.CircRNA could enter the blood circu-lation in the form of exosomes and microvesicles,and is not easily degraded by nuclease,and could exist stably in the blood circulation.The progression of gastrointestinal tumors is closely related to the expression level of circRNA in peripheral blood,and peripheral blood circRNA may be a potential novel non-invasive diagnostic marker for gastrointestinal tumors.This article reviews the research progress of circRNA in the diagnosis of gastrointestinal tumors,focusing on the clinical application value of peripheral blood circRNA in the diagnosis of gastrointestinal tumors.