Tumor suppressor miRNA-7 (miR-7) is found down-regulated in cancer tissues, but the underlying mechanism remains elusive. Recent studies demonstrated that circular RNA-7 (ciRS-7) acts as a sponge for miR-7 and thus can inhibit the miRNA-7 activity. This finding provided a new perspective for revealing the mechanisms of decreased expression of miR-7 in tumors. It is now believed that the ciRS-7/miR-7 axis not only has important biological functions, but participates in the occurrence and development of a range of diseases. Here, the authors present the research progress in ciRS-7/miR-7 axis regulating tumor growth and metastasis.