Abstract: The graft copolymers with high selectivity are synthesized by using self-made starch and acrylamide as raw materials.The hematite pure minerals with an average particle size of 8.00 μm are flocculated to form a floc with an average particle size of 37.75 μm, floc density of 2.92 g/cm³, floc porosity of 46.31%, floc strength of 1 362.41 Pa·mm² and fractal dimension of 1.95.The fine hematite floc is taken as the research object, and the flotation recovery rate is taken as the sorting indicators, and the influence of different influencing factors on the floc flotation recovery rate is investigated.The experimental results show that the maximum floc recovery rate is 92% when the pulp pH value is 8, the dosage of collector sodium oleate is 125 mg/L, the bubble diameter is 1.0 mm, and the stirring speed is 1 800 r/min.Through the influence of different conditions on floc flotation recovery rate, the law of its effect on floc flotation is obtained, which provided theoretical support for guiding practical production and application.