Abstract: Due to the continuous changes in the nature of the Bayan Obo raw ore, the physical properties of the rare earth concentrate have also changed, which affects the REO recovery rate of subsequent smelting process. The physical properties of Bayan Obo rare earth concentrate were studied through chemical multi-element, particle size, distribution, chemical phase and mineral composition analysis, and the influence of factors such as particle size, REO grade, iron and phosphorus ratio on the roasting and leaching of rare earth concentrate was investigated. The results show that the main impurity elements in the 53.11% rare earth concentrate of Bayan Obo are CaO, P₂O₅, F, TFe and SiO₂, the distribution rate of REO in the -30 μm particle size is 90.24%, the light rare earths proportion of lanthanum, cerium, praseodymium and neodymium is 97.89% totally, and the main rare earth minerals are bastnaesite and monazite; when the particle size of the rare earth concentrate becomes finer and the water immersion temperature, REO grade and iron-phosphorus ratio increase, All help to increase the REO leaching rate of roasted ore, the suitable mineral-acid ratio is 1:1.3~1.4, and the suitable iron-phosphorus ratio is 3:1~4:1. This study has ascertained the physical properties of the Bayan Obo rare earth concentrate, which provides a theoretical reference for the optimization of the subsequent smelting process.