CD22 is a Ⅰ type transmembrane glycoprotein specifically expressed on B lymphocytes. It is an important member of sialic acid-bound immunoglobulin-like lectin family and plays an important role in B cell regulation and humoral immunity as an inhibitory helper receptor. Autoimmune diseases are caused by autoimmune disorders. Abnormal activation of B lymphocytes and the formation of pathogenic autoantibodies is one of the most important features in autoimmune diseases. Treatment of autoimmune diseases with abnormal B cell proliferation and activation by CD22 monoclonal antibody has attracted attention, such as systemic lupus erythematosus and rheumatoid arthritis. This article reviews the molecular characteristics, functions, and research progress of CD22 in the treatment of autoimmune diseases.