The Cambrian is one of the globally significant phosphorite- forming periods, during which phosphorites were widely deposited around the world. However, most of these deposits have relatively low grades. In China, the Yunnan—Guizhou region is an important enrichment area for sedimentary phosphate deposits in the early Cambrian period. The Malu phosphorite deposit has a relatively high grade, with an average P2O5 content of 30.28% (n=10). Nevertheless, the genesis mechanisms of this deposit remain poorly understood. Therefore, this study focuses on the Malu phosphorite deposit in eastern Yunnan. It investigates the phosphogenesis environment, reveals the phosphogenesis process, and clarifies the key controlling factors, thereby providing a theoretical basis for a deeper understanding of the formation process of sedimentary phosphate- rich deposits.Methods: Based on detailed field investigations and integrated with petrographic and major—trace element geochemical analyses, this study explores the phosphogenesis environment and elucidates the key controlling factors.Through field investigations, petrographic analysis and geochemical studies.Result: The results show that the deposit is primarily composed of collophane and dolomite, with minor amounts of quartz, feldspar and iron oxides. The phosphorites commonly display sand grain structures with good particle sorting, sub- rounded to sub- angular, and a low content of mud—sand components. A sugar- like structure is also present at the top of the ore layer. Additionally, wedge- shaped cross- bedding and honeycomb- like structures are observed. The phosphorites exhibit a pronounced negative Ce anomaly, The Ce/Ce* value ranges from 0.313 to 0.795, with Ceanom values all less than -0.1, V/Cr ratios generally below 2, and relatively high Y/Ho values averaging 62.3. The geochemical signatures LaN/NdN>1, Y/Y*>1.5, and the decrease of MgO with increasing P2O5 content reflect that the Malu phosphate deposit may have undergone syn- sedimentary or quasi- sedimentary weathering and leaching during its mineralization process.ConclusionIt is concluded that the Malu phosphorite deposit formed in a shallow- water or even subaerially exposed environment, likely within the shallow beach facies of a tidal flat. Geochemical signatures suggest that the phosphorite was deposited in a relatively oxic environment.The main controlling factors for the high grade of the Malu phosphate rock deposit are the strong hydrodynamic conditions of reworking and the combined effects of weathering and leaching.