In order to study the mineral composition of weathering crust and the geochemical characteristics of trace elements and rare earth elements of the weathering section from Yaocun granite, Langxi, southern Anhui. Analyze the geochemical behavior of trace elements and the occurrence characteristics of rare earth elements. And further define the genetic mechanism of ion- adsorbed rare earth deposits in this area .Methods:Combined with field work and microscope observation, the weathering crust of Yaocun granite is stratified. Using LA- ICP- MS zircon U- Pb dating, XRD, whole rock trace element analysis and other methods, the geochemical behavior of trace elements and rare earth occurrence characteristics in the weathering crust of Yaocun granite were studied.Results: The LA- ICP- MS zircon U- Pb dating shows that the formation age of the Yaocun granite is 127.9±1.4 Ma, which is the product of the late Yanshanian magmatism in southern Anhui. The weathering crust can be subdivided into five layers: residual slope accretion (A), Strong semi- regolith (C1), transition layer (C2), Weak semi- regolith (C3) and bedrock (D). The total amount of rare earths is distributed in a "wave" pattern on the longitudinal section, and the distribution pattern of REE in each layer shows the inheritance of the bedrock. The REE of the bedrock is 338×10-6, and the REE of the semi- regolith is up to 642×10-6, which is about twice than bedrock. The weathering crust is enriched in LREE, and the fractionation of light and heavy rare earths is obvious (La/Yb)N=15.6). XRD results show that the weathering crust material is mainly composed of weathering residual main minerals (quartz, K- feldspar, plagioclase, biotite), clay minerals (kaolinite, halloysite, illite, gibbsite, etc.) and accessory minerals (zircon, apatite, titanite, etc.). Conclusions:The content of REE in the semi- regolith of the weathering crust of the Yaocun granite is significantly higher than bedrock, and the distribution patterns are consistent, indicating that the REE in the weathering crust have obvious inheritance during the development of the weathering crust. The clay minerals in the weathering crust are mainly illite, kaolinite and halloysite, and there is a positive correlation between REE and halloysite content. The weathering crust in this area is immature and is in an open system, and the migration of elements is seriously affected by environmental factors. The contribution of (including) rare earth minerals (especially titanite) to the REE in the weathering crust exceeds 50%, followed by plagioclase.