The invention relates to a preparation method of a lithium iron phosphate anode material, which is used for preparing the lithium iron phosphate anode material comprising an assistant material. The assistant material is made by spraying with a plasma spraying technology, the plasma spraying technology is completed by plasma spraying equipment, a spraying outlet of the plasma spraying equipment isconnected with a sealed spraying moulding cavity, the length of the spraying moulding cavity is 8 to 15 meters, and inert gases are filled in an inner cavity of the plasma spraying equipment and the spraying moulding cavity. Reaction raw materials can be directly molten, and the lithium iron phosphate anode material with high sphericity, uniform ingredients and stable performance can be instantlyprepared.