The cell viability and functions are finely regulated through various biochemical modification occurred in the metabolism process. Enzymatic glycosylation is a common molecular modification in metabolic regulation and has an important impact on maintaining and regulating cells functions. Glycosyltransferases are enzymes that catalyze the transfer glycosyl moieties from activated donor to a wide and diverse range of acceptor molecules. The glycosylation of the acceptor molecules lead to changes of their intracellular properties such as stability, solubility and regional localization, and thus played important roles in many bioprocesses including cell cycles, signal transduction, protein expression, resistance responses, and clearance of pollutants. The classification, naming and catalytic mechanism of glycosyltransferase superfamily are briefly introduced. Then the glycosylation of protein and small molecule compounds and their functions in metabolic processes are reviewed, when the glycoside was transferred to intracellular biomolecule proteins and small molecule compounds. At last,the application prospects of glycosyltransferases and glycosylation reactions in the fields of human health pharmaceutical products, industrial catalysis, food and agriculture are looked forward.