The invention relates to the field of inorganic material preparation, specifically to micro-and nanoscale ferric phosphate, its solvent extraction-microemulsion preparation method and an application thereof. The method comprises the following steps of: a, preparing a microemulsion containing Fe<3+>: 1) preparing an aqueous solution of ferric salt and adjusting pH to 1-4; and 2) mixing organic phosphonic (phosphine) acid extractant or organic carboxylic acid extractant and an organic amine extractant to obtain a mixed extractant with the concentration of 0.1-0.5 g/mL; performing mixed extraction on the aqueous solution of ferric salt and the mixed extractant to obtain the microemulsion containing Fe<3+>; b, preparing a PO4<3-> microemulsion: performing a mixed extraction on a phosphoric acid solution and the mixed extractant to obtain the PO4<3-> containing microemulsion; and c, preparing the micro-and nanoscale ferric phosphate: mixing the microemulsion containing Fe<3+> and the microemulsion containing PO4<3->, stirring, reacting to generate a white precipitate, and carrying out solid-liquid separation to obtain the micro-and nanoscale ferric phosphate. The advantage of the method is that the preparation technology is simple, and the product has excellent electrochemical performance.