Abstract:circular RNA (circRNA) is a group of endogenous noncoding RNA with closed loop structure, which widely and very stably exists in all eukaryotes. It has the features of construct stability, sequence conservative and tissuespecific expression. Prior studies have discovered that circRNAs could act as microRNA (miRNA) sponge to regulate the expression of them. Besides, some circRNAs could regulate gene expression by interacting with proteins. Some studies have shown that circRNAs are not only participated in physiological processes, such as plant hormone signal transduction, but also play an important role in the process which response to biological stress in plants. In this paper, we reviewed the classes and biogenesis of circRNAs, as well as the function of circRNAs. In addition, we discussed the undiscovered issues and the meanings of existence about circRNAs. As research continues, we believe that it can provide theoretical reference for the formation mechanism and gene regulatory networks of circRNAs in plants.