Abstract: The annual output of the by-product，hydrofluosilicic acid，as well as the recycling development status of its ‘fluorine and silicon’was introduced. Especially，the present research status，including raw materials，reaction mechanism，process flow，difficulties，key points，and main equipments of the preparation process of green tire grade silica by the reaction between hydrofluosilicic acid and sodium silicate was described in detail，and a comprehensive evaluation on the process was also made.The differences in the quality of silica products by traditional method and by hydrofluosilicic acid-water glass pro- cess were compared，which will be a technical support for China′s silica quality improvement and development.

Key words: hydrofluosilicic acid, sodium silicate, silica, tires