As an important part of the “ Sanjiang” metallogenic belt, the Lanping Basin contains numerous ore deposits whose host rocks are associated with the Eocene Series. In order to clarify the relationship between the Eocene and ore-bearing wall rocks in the basin, and to further provide basic support for regional metallogenic research and sedimentary evolution analysis, the Guolang Forma- tion of the Eocene in Lanping Basin was taken as the research object, the sedimentology, mineralogy, and sedimentary geochemistry were adopted to investigate grain size characteristics, provenance properties, tectonic setting, and sedimentary environment. The results show that: trace element spider diagrams indicate that elements such as Sc, V, Cr, Co, Ni, Th, U, Rb, Sr, Cs, and Ba exhibit vari- ations in enrichment and depletion across different samples; rare earth element ( REE) distribution patterns display an obvious “ steep left and gentle right” trend; ratios of Sr / Ba, V / Ni, and V / ( V + Ni) suggest an arid, oxidizing environment with low salinity; discrim- inant diagrams including Zr-Th, La-Th-Sc, and Th-Sc-Zr / 10 reflect a continental island arc tectonic setting; La / Yb-REE and La / Th- Hf diagrams illustrate that the source rocks are sedimentary rocks, with provenance mainly derived from felsic source areas, followed by mixed source areas of felsic / basic rocks; probability cumulative curves show a “ one jump, one suspension with transition” pattern,dominated by suspension; both SK-σ1 scatter plot and C-M diagram confirm that the sedimentation is dominated by fluvio-lacustrine traction current and low-energy gravity flow. It can be seen that the revelation of the sedimentary evolution characteristics of the Eocene Guolang Formation in the Lanping Basin and the clarification of its internal relationship with regional ore-bearing wall rocks can provide a reference for the in-depth exploration and mineral resources prospecting in the future.