Abstract: Carboniferous Benxi bauxite in Shanxi Province is also called the North G layer of bauxite.Through the analysis of its tectonic background and ancient geography and the distribution of bauxite,we point out that the Shanxi bauxite deposits are mainly distributed in the ancient land,ancient island edge mineralization basin,and the better the mineralization basin closeness the more advantageous for the mineralization.Ancient land wide outcropping of aluminum silicate rocks by weathering and decomposition,the elements such as K,Na,Ca,Mg among them are drenched and lost,the elements such as Fe,Al,Ti,Si,etc.are relatively collected and left in the red weathering crusts.Through short distance mechanical transgressive action they are transported to sedimentary basin sediments,And through analysis of the surrounding material components of bauxite composition,it is further confirmed that the deposition in the edge of the ancient land of the original bauxite layer is buried below the surface in the restore environment.Deposit and mineralization are formed after drenching and straining and taking off silicons by acid solutions such as groundwater,surface water,etc.And then they are lifted by the earth's crust,through the role of seepage and oxidative modification to the original bauxite to achieve the enrichment of bauxite.And the bauxite is distributed on one side of the gentle slope close to the edge of ancient land.In the valley of the two sides of the low-lying mountain ore bodies are rich.While deep bury is not favorable for mineralization.