The invention discloses a method for preparing high-purity manganese phosphate from low-grade rhodochrosite leaching liquid and belongs to the hydrometallurgy field. The impurity content of the low-grade rhodochrosite leaching liquid is high, the technical difficulty of impurity removal is high, and the process is complicated. The method for preparing the high-purity manganese phosphate from the low-grade rhodochrosite leaching liquid is short in technological process and mainly includes the following two steps that firstly, sodium phosphate is added into sulfuric acid leaching liquid of rhodochrosite, the pH value of a solution is controlled between 3 and 3.5, sufficient stirring is performed, precipitate is removed in a filtering manner, and a preliminarily purified manganese sulfate solution is obtained; and secondly, sodium phosphate continues to be added into the preliminarily purified manganese sulfate solution, a final pH value of the solution is controlled between 4.0 and 4.5, sufficient stirring is performed, filtering and repeated washing are performed, and a high-purity manganese phosphate product is obtained. The method is simple in process operation and easy to control, the prepared manganese phosphate is high in purity, feasibility of evaluation in the aspects of economy, technology, environment and the like is high, and a new path is provided for development and application of the low-grade rhodochrosite.