As a typical solid waste in the electrolytic manganese industry，electrolytic manganese slag produces leachate containing manganese ions during the storage process，among which manganese has high recycling value. In this paper，the preparation method and morphological control of ultrafine manganese carbonate recovery in electrolytic manganese slag leachate are studied， and the effects of reaction temperature，reaction time，MnSO₄ concentration，Mn²⁺/Na⁺ ion molar ratio and other influencing factors on the morphology and particle size of manganese carbonate are characterized by laser particle size，SEM，XRD and other physical characterization methods. The results show that with the increase of temperature，the laser particle size of manganese carbonate particles decreases，and the calcium and magnesium ion content is relatively stable，with mass fractions of 0.07% and 0.06%， respectively. When the reaction temperature is 25 ℃， the reaction time is 20 min，the rotation speed is 600 r/min，and the molar ratio of Mn²⁺/Na⁺ is 1∶2， the micron-scale MnCO₃ powder with higher purity can be directly obtained in the experiment，and the ion fraction of Ca²⁺ and Mg²⁺ impurities is 0.04%，and the separation of Ca²⁺，Mg²⁺ impurities and Mn²⁺ is realized in the experiment.The grain size change law calculated by Scherrer formula is basically the same as that of the laser particle size test， and the primary particle morphology of SEM is a cube of 50 nm. The high concentration of Na + ions inhibits the secondary growth of manganese carbonate，and the concentration of MnSO₄ and the reaction temperature cause the morphology of manganese carbonate particles to change from well-dispersed cubes to spherical powders grown in multi-cube stacks. The research results can provide a low-cost and environmentally friendly technical path for the recovery of manganese carbonate powder from electrolytic manganese slag leachate.