The invention discloses a method for preparing precursors of lithium titanate and lithium iron phosphate by comprehensively using ilmenite, which comprises the following steps of: 1) separating the ilmenite, namely crushing the ilmenite, leaching the ilmenite with hydrochloric acid, filtering the ilmenite to obtain a residue and a filtrate; 2) preparing the precursor of the lithium titanate, namely washing the residue prepared by step 1) with the hydrochloric acid, adding the washed residue in aqueous alkali, cooking the mixture, filtering the mixture after cooling, and then adding the obtained filter residue in the hydrochloric acid, cooking the mixture, and filtering, washing, drying and calcining the mixture after cooling to obtain the precursor of the lithium titanate; and 3) preparing the precursor of the lithium iron phosphate, namely taking the filtrate prepared by step 1) as a raw material, adding iron powder to reduce ferric iron, diluting the reduced filtrate, adding a complexing agent and a precipitant into the diluted mixture, controlling the pH value of the system, reacting the mixture at 30 to 80 DEG C, aging the reacted mixture, and filtering, washing and drying theobtained precipitate to obtain the precursor of the lithium iron phosphate. The method is wide in raw material source, simple in process flow, good and stable in product quality, low in cost and comprehensive and full in use of the ilmenite.