The immunoglobulins (Igs), most of them are glycoprotein, play an important role on humoral immune. The structure, composition of oligosaccharide conjugated with protein directly effect the function of Ig. For example, abnormal oligosaccharide can result in some autoimmune diseases. The correlation between autoimmune disease mechanism such as IgAN and RA and aberrant glycosylation is given detailedly in structure, molecular mechanism, enzyme and clinic etc. And provide the theory basis on building a sensitive and specific diagnosing method.