Abstract: Process principles and conditions of the method for producing anhydrous hydrogen fluoride and sodium silicate using the by-product hydrofluosilicic acid of phosphate fertilizer were studied.All the indexes of hydrofluoric acid had reached the requirements of GB 7744—2008，and sodium silicate was used as low-grade phosphate rock flotation inhibitor.When P2O5 grade of ore was 22.71%，mass fractions of MgO and SiO2 were 3.21% and 22.17% respectively，after being a positive flotation-rough-fine sweep and a reverse flotation roughing operations，beneficiation indicators，such as P2O5 grate of the final concentrate of 29.99%，and MgO mass fraction of 0.85% were obtained.The process had the characteristics of economic and technical feasibility，fluorine and silicon resource recycling，energy conservation，and environmental protection etc..

Key words: hydrofluosilicic acid, anhydrous hydrogen fluoride, flotation inhibitor