The invention discloses a beneficiation method of high carbonate-contained mixed iron ores. The ore grinding and the weak magnetic separation-strong magnetic separation are performed for raw ores to obtain weak magnetic separation iron concentrates and strong magnetic separation iron concentrates; the strong magnetic separation iron concentrates are finely screened to obtain undersize qualified iron concentrates; oversize products are fed in a preliminary classification-regrinding-strong magnetic separation process to remove qualified tailings to obtain strong magnetic separation rough concentrates; the strong magnetic separation rough concentrates are fed in a direct flotation operation to obtain direct flotation iron concentrates; and the qualified tailings are removed to finally obtain mixed iron concentrates with the TFe grade of more than 58.5%, the SiO2 content of less than 4% and the alkali ratio of not less than 0.9. The beneficiation method has such advantages as simple process flow, low beneficiation cost, high beneficial element-calcium and magnesium content in the final mixed iron concentrates, low impurity-silicon and aluminum content, high iron recovery rate, high alkali ratio, low loss of fine particle iron ores, stable index and low medicament consumption, and facilitates protection of the environment and saving of resources and energy.