<p>Manganese is an important strategic resource for the new energy industry, and the preparation of high-purity manganese sulfate is crucial for lithium battery positive electrode materials. This study aims to thoroughly remove Ca²⁺ and Mg²⁺ impurities in rhodochrosite acid leaching solution, and proposes a directional purification method based on MnF₂ precipitant. Through single factor experiments and response surface optimization, the effects of MnF₂ addition, temperature, pH, and reaction time on impurity removal have been systematically studied. Under the optimized conditions (MnF₂ addition 2.35 times the theoretical value, temperature 86.94 °C, pH 4.0, reaction time 45.92&#xa0;min), the removal rates of Ca²⁺ and Mg²⁺ reached 99.93% and 98.98%, respectively. Combining thermodynamic analysis with an E-pH diagram to explore the precipitation mechanism of impurities, the results show that the preferential precipitation of CaF₂ and MgF₂ originates from the strong coordination ability of Ca²⁺/Mg²⁺ with F^- (hard and soft acids and bases, HSAB, theory) and the ionic radius matching effect (r⁺/r⁻ = 0.75). In addition, MnF₂ was efficiently recovered by water-washing precipitation–evaporation crystallization method, and battery-grade manganese sulfate was successfully prepared. This study provides theoretical support and technical reference for the efficient purification of rhodochrosite leaching solution and the green preparation of battery-grade manganese sulfate.</p>