Abstract Fluorine is a major pollutant in the conversion of phosphate rock to nitrophosphate fertilizer. In this paper, removal of fluoride in the nitrophosphate process was investigated. Fluoride ion-selective electrode and acid–base titration method were employed to determine the fluoride content and species in the actual acid digestion liquor. It was found that fluoride was present in two forms of H 2 SiF 6 (0.78 wt% F − ) and HF (0.10 wt% F − ). Precipitation tests were performed both in pure fluoride solution (H 2 SiF 6 + HF + H 2 O) and actual acid digestion liquor using KNO 3 as precipitant. Influences of reaction time, temperature and KNO 3 addition were studied. The precipitates obtained were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray fluorescence (XRF). Precipitation experiments revealed that the addition of KNO 3 would remove the fluoride effectively, and the obtained precipitates were the high-purity K 2 SiF 6 . The maximum fluoride removal efficiency could reach 88.52% at 25 °C when 400% excess of KNO 3 was added in the pure fluoride solution after 1 h. However, the fluoride removal efficiency reached only 70.22% in actual acid digestion liquor under the same experimental conditions. These obtained results are important and meaningful for the sustainable development of nitrophosphate fertilizer.