The invention provides a method for determination of the content of ferroferric oxide, wherein the method comprises the following steps: (1) dissolving a Fe3O4 sample with concentrated hydrochloric acid and 30% hydrogen peroxide and drying by distillation; (2) dissolving residues by deionized water; (3) adding quantitative potassium iodide into the reactant solution, keeping in a dark place and placing for 30 min; and (4) carrying out quantitative titration by a 0.1 mol/L sodium thiosulfate standard solution under display of a starch indicator until blue disappears, and thus achieving an end point. The method for determination of the content of ferroferric oxide has the advantage of stable and accurate detection data, achieves good results, and has important application value.