The invention discloses a preparation method of Co3O4 for batteries, Co mineral is used as Co raw material, after purified the Co liquid is obtained, complexing-homogeneous sedimentation method is adopted to prepare precursor, i.e. the Co liquid is prepared into the complexing Co salt solution, and then added with precipitator solution, the synthesis of the precursor is controlled to obtain single-dispersion sedimentation precursor so as to make the production and growth of the nucleation be separated, and then sintered under high temperature, the precursor is thermally decomposed to obtain the Co3O4 for batteries finally. The prepared Co3O4 powder has good flow property, even granularity and can utilize DCS system to adjust process parameters accurately to realize the control (D50=3um-6um, 6um-9um,9um-12um), the tap density can reach 2.5g per cubic centimeter to 3.5g per cubic centimeter, microcosmic shape is single-crystal or like spherical, moreover the invention has the advantages of high chemical purity, good electrochemical performance, and no environmental pollution. The invention has simple process, stable product quality, low cost, and can adapt for the requirements of material performance and cost of various lithium cobalt oxide manufacturing factory.