The invention discloses a preparation method of iron manganese phosphate. The preparation method comprises the steps of preparing a base solution, and adding a ferromanganese mixed solution and an ammonium hydrogen carbonate solution to the base solution in a stirring condition, and after adding is completed, continuously performing a stirring reaction to obtain carbonate paste; performing solid liquid separation on the carbonate paste, washing the filtering residue by hot pure water, and then adding the product into the pure water to be subjected to slurrying, and next, adding a phosphoric acid solution and hydrogen peroxide into the slurry material at the unfirm speed synchronously, and next, performing heating to obtain iron manganese phosphate paste; performing solid liquid separationon the iron manganese phosphate paste, washing the filtering residue by hot pure water, and then performing vacuum drying, screening and iron removing to obtain iron manganese phosphate; and adding iron manganese phosphate into a mixed solution of anhydrous alcohol and butyl titanate, performing grinding, and next carrying out spray drying on the paste to obtain titanium-coated iron manganese phosphate. The titanium-coated iron manganese phosphate material obtained in the invention has small grain diameter, high tap density, small specific surface, and uniform grain diameter distribution, without causing a ferromanganese segregation phenomenon.