Abstract: The Yangchang phosphorite deposit in Zhenxiong County, northeastern Yunnan Province is a newly discovered super-large high-quality phosphorite deposit with large reserves (predicted prospective resources of 13 billion tons), large ore body thickness (up to 30 meters) and excellent ore quality (low-magnesium high-calcium limestone-type phosphate rock).The phosporite deposit is located in the semi-closed shallow-water platform facies of the carbonate platform Weining-Zhaotong fold-punch belt Xiaotan-Yangchang polyphosphorite basin in front of the southwestern margin of the Upper Yangtze Continental Block, which belongs to typical Early Cambrian marine sedimentary phosphorite deposit.The study of paleostructure, lithofacies palaeogeography and phosphorite-forming conditions indicates that Suijiang-Yongshan-Zhaotong phosphorite-forming area in the west of the Xiaotan-Yangchang polyphosphorite basin have found medium-sized phosphorite deposits such as Wuji, Jinshachang and Guanfang in Yongshan County.Located in the Zhenxiong-Weixin phosphorite-forming area, east of the basin.The Yangchang phosphorite deposit has a similar metallogenic background, with good metallogenic geological conditions and great prospecting potential.Based on the comprehensive analysis of the geological background, paleostructure and lithofacies paleogeography of the Yangchang phosphorite deposit, the regional phosphorite mineralization law and prospecting direction are summarized, which provides the basis for prospecting breakthrough of the Early Cambrian marine sedimentary phosphorite deposits at the southwestern margin of the Upper Yangtze Block.