Orthologs of UBL5 almost occur in every eukaryotic genome. UBL5 plays an important role in H2B monoubiquitination, pre-mRNA splicing, cell cycle regulation, energy metabolism, stress,etc. UBL5 is a novel class of the UBL protein family.The tertiary structure of UBL5 is similar to that of ubiquition and ubiquition-like proteins;however, UBL5 contains a C-terminal di-tyrosine motif instead of the conserved di-glycine. All those are based on plenty of references and the research about cloning UBL5 from Xanthoceras sorbifolia Bunge. in our laboratory. This paper reviews the latest results about UBL5 gene in the aspects of its cloning, structure and function.