Abstract:circRNA is a kind of covalently closed circular RNA molecule and mainly arises from backsplice. circRNA has a variety of biology characteristics and functions. Especially， it can work as microRNA sponge to be involved in miRNA-associated diseases， and be regarded as a potential disease screening biomarker. circRNA is widely existing in living bodies， and the majority of circRNA is exonic circRNA. Here， we briefly summarize several kinds of circRNA and their biosynthesis， properties， functions and applications， aiming to help researchers comprehend its research progress and prospective application.