The invention discloses a technology for producing sodium fluosilicate. The technology comprises the following steps of 1, preparing a sodium sulfate solution having the mass content of 26 to 32%, 2, adding fluosilicic acid having the mass content of 8 to 14% into the sodium sulfate solution with stirring, 3, controlling a use amount of the sodium sulfate solution, adjusting a use amount of fluosilicic acid so that compared with a theoretical use amount calculated by a chemical equation, the use amount of fluosilicic acid is increased by 3 to 6%, 4, carrying out crystallization after a reaction of sodium sulfate and fluosilicic acid, 5, washing, separating sodium fluosilicate crystals, and carrying out centrifugal drying, and 6, recovering sulfuric acid and fluosilicic acid. The technology reduces unit consumption of sodium sulfate, reduces sodion content of sewage and realizes recovery of sulfuric acid in the sewage. Compared with the prior art, the technology has high efficiency, is environmentally friendly, simple and convenient, and has low salt consumption and a low cost. Sewage produced by the technology for producing sodium fluosilicate can be directly recovered and used.