Abstract: The Mianning-Dechang rare earth metallogenic belt in Sichuan is one of the most important rare earth metallogenic belts in China, with the Mianning Maoniuping REE deposit and the Dechang Dalucao REE deposit being the largest developed mines on this metallogenic belt. The Dechang Dalucao REE deposit is located in Dalucao Township, 31.6 km away from Dechang County town at a bearing of 221°. A large area of quartz diorite is exposed in the region, with multiple stages of intrusion by syenite stocks （veins）. Two ore bodies, labeled as No.I and No.III, have been identified in the area. The No.I ore body, which is currently being developed, mainly occurs within alkaline syenite and calcite carbonatite, presenting a flat columnar shape and large scale. The ore primarily consists of semi-automorphic fine-medium grained structures, cataclastic textures, conglomerate fabrics, and disseminated textures. The beneficial components are mainly cerium and lanthanum, occurring in the form of fluorocarbon cerium mineral, accompanied by Sr, Ba, F, Pb, while the harmful components ThO₂ and U are present in trace amounts. The average REO content of the deposit is 3.64%. The hydrogeological conditions, engineering geological conditions, and geological environmental quality of the mining area are moderate. This deposit is classified as a crypto explosive breccia type REE deposit.