Many studies have revealed that circRNAs have unique expression signatures and contribute to biological processes through a variety of functions, for example, acting as transcriptional regulators/microRNA(miRNA) sponges/protein templates, and serving as protein decoys, scaffolds and recruiters etc. The unique structure and broad expression of circRNAs makes them potential candidates for diagnostic biomarkers and therapeutic targets of a variety of diseases, such as cancers, cardiovascular diseases, neurological disorders and autoimmune diseases etc.