The raw material for producing caustic soda is industrial salt. Chlor alkali enterprises in eastern coastal areas mainly use sea salt, while chlor alkali enterprises in northwest areas mainly use lake salt. The price of industrial salt has a little fluctuation, and it has a limited proportion in the production cost of caustic soda. At present, ion-exchange membrane electrolysis is a main way to manufacture caustic soda. 2200-2400 kilowatt hours will be consumed when producing a ton of caustic soda according to the difference between new and old of ionic membrane. Caustic soda, as a very basic industrial raw material, is mainly used in petroleum refining, printing and dyeing, texitle, paper-making, soil treatment, chemical reagent, rubber, metallurgy, pottery and porcelain and some other areas.