Abstract: The preparation of the iron oxide red seed by ammonium process with FeSO4 as raw material, and the influencing factors in preparation process has been studied in details.The results showed that under conditions of the concentration of ferrous sulfate of 30 g/L, reaction temperature 16 ℃, the volume of air 20 L/h, the addition of the diluted ammonia water 34 mL/L (molar ratio of NH₃H₂O and FeSO₄ 2.17∶1), and the adding rate of diluted ammonia water 0.45 mL/s, the best seed are generated with short reaction time.

Key words: Iron oxide red seed, Ammonium process, Interfering factors