Abstract: The medium-poor oxidized ore in Bayan Obo deposited for many years contains iron,rare earth and other composition, which is difficult to be separated efficiently by conventional process,but the iron can be recovered efficiently by hydrogen- based ore phase transformation-magnetic separation process. In order to understand whether the phase conversion process of hydrogen-based ore affects the floatability of rare earth minerals in rare-earth-rich iron tailings,a systematic beneficiation test was carried out. The results showed that under the conditions of 506E dosage of 4 200 g/ t,sodium silicate dosage of 1 800 g/ t and slurry temperature of 65 ℃,the closed circuit flotation with two roughing and three cleaning achieved a rare earth ore concentrate with an REO grade of 59. 00% and an REO recovery of 67. 91%. Chemical composition analysis and X-ray diffraction showed that the main components were rare earth oxides (Ce7O12),monazite and a small amount of fluorite. The rare earth elements were effectively enriched in the concentrate,demonstrating that the hydrogen-based mineral phase transformation process did not adversely affect the flotation recovery of rare earth elements.