Objectives and Methods: In order to understand the mechanism of phosphate enrichment and deposition in the Early Cambrian phosphorite deposits in the Yangtze region of China, the large phosphate deposit in Xiaogou, Leibo County, southwestern Sichuan Province, was systematically studied by confocal laser Raman and LA- ICP- MS. Results:The results show that the phosphorous block rocks in Xiaogou deposit are mainly composed of collophanite, carbonate minerals, organic matter, siliceous and a small amount of pyrite.The development of microorganisms in ore was identified as Eoentophysalis and Obruchevella. In situ REE analysis of LA- ICP- MS shows that all the sites have obvious negative Ce anomalies, indicating the bottom water and pore water conditions of Oxid—Suboxic during the sedimentary mineralization process.Conclusions: It is concluded that the mineralization is closely related to the organic matter sedimentation and extracellular polymeric substances (EPS) : ① Under the conditions of Oxid—Suboxic bottom water, the sedimentation of biological organic matter and its rapid decomposition during burial lead to the supratsaturation of dissolved phosphate in pore water, which is the main cause of phosphorus enrichment and precipitation; ② Extracellular polymeric substances (EPS) adhere to cells and organic debris, accelerating the aggregation and settlement of biological organic matter. In the burial process, EPS provides a large number of nucleation sites for phosphorus aggregation, and promotes the rapid precipitation of collophanite.