Abstract: microRNA (miRNAs) is short non-coding RNA molecules with length of 19~25 nt. Previous studies find that it has a variety of biological functions, and it regulates most cell process. With further research on miRNAs, more and more functions have been discovered and characterized. miR-125a is a hot point of miRNAs researches, and it works as a tumor suppressor to inhibit growth and metastasis of tumor cell. This review focuses on the advances in miR-125a functions and related diseases, which will help us fully understand the biological function and target of miR-125a, in order to provide theoretical basis for the clinical application of miR-125a.