Many RNAs can undergo post-transcriptional modifications, and recent studies have revealed that the nontemplated 3′-end uridines addition(Uridylation) on RNAs may also be a ubiquitous and conserved modification mode previously underappreciated, which occurs in many RNA substrates, such as polyadenylated mRNA, 5′ fragments of mRNA cleaved by siRNAs or miRNAs, histone mRNAs, most of currently discovered small RNAs, U6 snRNA, transcriptional start site-associated RNAs, spliced introns, and so on, ranging from algaes to humans. These modifications not only play important roles in marking RNA for degradation, promoting or inhibiting RNA biogenesis process, altering RNA activity efficiency and acting as a quality control mechanism of mRNA, but also associate with several human diseases, for example, cancer. In this review, recent achievements of uridylation on small RNAs, mRNA or its cleaved fragments, histone mRNAs and U6 snRNA will be discussed. The applicative perspective of these modifications will be discussed.