Abstract: In this paper, research is made on the reverse flotation in different water hardness conditions. The influence of the pH and metal ions like Ca²⁺ and Mg²⁺ on hematite reverse flotation is investigated. Experimental results clearly show that the adsorption ability of Ca²⁺ and Mg²⁺ on quarts is increased along with pH increasing, and in the hematite reverse flotation process, the optimum pH is decreased along with increasing of metal ions density. In the condition of ultra hardness of the flotation process water, the corresponding ways are reduce the usage of CaO and reduce the minimum pH Value.