The invention discloses a preparation method of titanium-doped lithium iron phosphate. The method includes introducing titanium tetrachloride into a phosphoric acid solution, then putting the reactionslurry into a sealed reaction kettle, and carrying out reduced pressure evaporation until water is completely evaporated to dryness; pouring out the evaporated powder, mixing lithium carbonate through jet milling, mixing, slurrying, levigating, spraying and calcining to obtain a primary calcined material; adding the primary calcined material into a polyethylene glycol solution, stirring and slurrying to obtain a slurried material, then adding a ferrous sulfate solution, a phosphoric acid solution and an ammonia water solution into the slurried material together, and filtering, washing and drying the reaction material to obtain an iron-titanium mixture; and mixing the iron-titanium mixture with lithium carbonate and a carbon source, slurrying, grinding, spraying and calcining to obtain a material, carrying out jet milling, screening and iron removal on the material to obtain the titanium-doped lithium iron phosphate. According to the invention, the uniformly titanium-doped lithium ironphosphate can be obtained, the discharge voltage platform is high, the compaction density is high, and the energy density is high.