Abstract: Based on industrial production data, the entire production process of iron phosphate was established in the Aspen Plus V14 software, with ferrous sulfate heptahydrate and ammonium dihydrogen phosphate as the main raw materials and hydrogen peroxide as the oxidant. The oxidation reaction occurred to generate iron phosphate dihydrate, and the iron phosphate product was obtained after washing, drying and calcination. Aiming at the problem of high-water consumption in the production process of iron phosphate, the research on water system integration and optimization was carried out by changing the number of horizontal screw centrifuges and optimizing the water usage in the raw material dissolution process and the washing process. The process simulation results show that the output of iron phosphate is 25,200 tons per year, and the relative error with the design value is 0.8%. Taking into account the consumption of pure water and equipment costs comprehensively, using four horizontal screw centrifuges yields the best result. Through water system integration, the consumption of pure water is reduced by 85.88%, and the wastewater discharge during the washing process is reduced by 99.24%.