Carboxymethyl starch (CMS), a kind of transparent colloid, is easy to dissolve in the water, which can be used extensively in the industrial department such as petroleum, textile, paper making, synthetic washing, medicine, food, drink, toothpaste to make filtrate reducer of mud, sizing, paper strengthening agent, dirty-carrying agent, disintegrating agent, binding agent, emulsifying agent, stabilizer, and so on. The standard of various trades can be executed according to various requests of customers.