Abstract: Maoniuping deposit is the third largest rare earth element(REE) deposit in the world after Bayan Obo in China and Mountain Pass in the United States. Recently, a new ore-prospecting break was made in the periphery of Maoniuping deposit, and two types of thick and rich concealed rare earth ore bodies have been discovered under Quaternary sediments (more than 50 m thick) in Longjiagou area. The first type is the bastnaesite-aegirene-fluorite-barite, and the second type is the bastnaesite-fluorite-barite-calcite. The total thickness (apparent thickness) of the bastnaesite-fluorite-barite-calcite type vein exceeds 100 m, and the average REE grade is 4.6%. The X-ray diffraction analysis result shows that the ore was mainly composed of calcite (40%~75%), fluorite (25%~58%), barite (5%~25%) and bastnaesite (1%~16%). Based on the texture, structure and mineral composition of the ore, the authors divided its formation process into two stages. The ore in the early stage was mainly medium coarse granular structure, and massive structure and taxitic structure, while the ore in the late stage was medium-fine grain brecciform structure and flow structure. The discovery of this new type of ore body with high-grade, easy to mining and beneficiation is an important breakthrough in rare earth mineral exploration since the implementation of the new round of prospecting breakthrough strategy. It is suggested that further geological prospecting for REE ore of bastnaesite-fluorite- barite-calcite type should be undertaken in Maoniuping mining area and its periphery.