Ammonium fluosilicate was prepared with ammonium fluoride solution and fluorinated silica slag as raw materials by chemical dissolution.The effects of reaction temperature,reaction time,concentration of ammonium fluoride solution and material ratio（amount-of-substance ratio of ammonium fluoride to silica） on the yield of ammonium fluosilicate and conversion of silicon dioxide were investigated.The experimental results showed that the reaction temperature was 93 ℃,the reaction time was 60 min,the mass fraction of ammonium fluoride solution was 20%~30%,the materials ratio was 6∶1.1 and the stirring speed of reaction system was at 200~300 r/min.Under the conditions,the yield of ammonium fluosilicate and the conversion of ammonium fluoride can be controlled over 90%.