Glycosylation is one of the most common and most important methods to modify cell surfaces.Glycosylation mutants often influence the products' structure and change chemical characteristics of cell surfaces.Regulation of the activity of glycosylation-re- lated enzyme through genetic methods and small chemical molecules will alter glycosylation process and disclose the impact of glycosy- lation products on organism health and the relationship between glycosylation mutants and diseases.