Etherification starch is starch molecules of the hydroxyl and reactivity matter reactions of the generation of starch replace silyl ether, including hydroxyl alkyl starch, carboxy methyl starch, cationic starch, etc. Because the etherification effect improve starch viscosity stability, and in strong alkali conditions ether hydrolysis not cause key, therefore, etherification starch in many industrial fields to the application. Carboxy methyl starch (CMS) is a type of natural products of anionic degeneration of the body, is soluble in cold water natural polymer electrolyte ether together. At present has wide 'the cMS should just in food, medicine, oil, daily chemical, textiles and paper and adhesives, paint industry