Abstract: The hydroxyl–alkyl and cationic esterification modification of guar gum is introduced. Research is focused on grafted copolymerization of guar gum with various ethylene monomers such as acrylamide，acrylonitrile，etc. The optimum parameters，such as grating ratio，efficiency etc. are listed. Guar gum derivatives are used as retention and drainage aids，as well as dry strength agent in the papermaking industry. The potential application in the future is pointed out.