Abstract: <FONT face=Verdana>Production process of producing cryolite and by-producing high-quality silica white with sodium hydroxide-sodium fluosilicate (NaOH-Na2SiF6) method was researched and factors influencing the process that NaOH decomposing Na2SiF6 to produce silica white were confirmed.NaOH (mother liquid will be used in the real production cycle) with low concentration reacted with Na2SiF6 at a certain condition and silica paste as well as sodium fluoride solution was then obtained.Silica paste was washed and dried to prepare silica white product and sodium fluoride solution was pumped into storage tank for further synthesis after secondary filtration.NaOH solution at a certain concentration preheated to 100 ℃,and then add aluminium hydroxide with calculated amount.Stirring the solution till it turned to clear and sodium aluminate solution will be prepared.Adding sodium fluoride solution and sodium aluminate solution in definite proportion into a synthetic tank,controlling temperature and cryolite product will be finally obtained through filtration after completion of the reaction.Cryolite product produced by this method had better fluidity,acceptable quality,and suitable for start-up of aluminum electrolysis comparing with that produced by ammonia-sodium fluosilicate method.Therefore,it has good market prospect.Moreover,wastewater can be recycled and it has less environmental pollution. </FONT>