The invention discloses a method for treating lithium iron phosphate waste, and belongs to the field of waste treatment. The method comprises the steps: adding the lithium iron phosphate waste to an alkali solution, carrying out a reaction, and filtering and washing to obtain a first filtrate and a first filter residue; adding the first filter residue to an alkali, mixing uniformly, roasting, andintroducing air to obtain a roasted material; adding the roasted material to hot pure water, stirring, and then filtering to obtain a second filtrate and a second filter residue; adding the second filter residue to hot pure water, washing, and mixing the obtained washing water with the second filtrate to obtain a third filtrate; drying, crushing and screening the obtained washed residue to obtainiron oxide red; adding the third filtrate into a phosphoric acid solution under stirring, adjusting the pH of the solution, cooling, and then filtering, to obtain a third filtrate residue and a fourthfiltrate; and adding the third filtrate into hot pure water, washing, drying and screening, and discharging iron to obtain battery-grade lithium phosphate. The method has the advantages of simple treatment, short process flow, less waste water production amount, high material recovery rate, low cost and high profit.