MicroRNAs(miRNAs) are a class of small non-coding RNA molecules that negatively regulate gene expression at the post-transcriptional levels by base pairing with target mRNAs which leads to mRNA cleavage or translational repression in eukaryotes. A large number of studies show that miRNAs play a vital role in physical development, cancer, cell differentiation, proliferation and apoptosis, lipid metabolism. Recently, numerous research findings about miRNAs have been gained in aquatic animals. However, no comprehensive summary has been reported in this aspect so far. This paper reviews the recent research progress of miRNAs in aquatic animals. The results show that miRNAs present diverse biological functions in aquatic animals. The aim of this review is to provide basic references for analysing prospects of further development about miRNAs in aquatic animals.