In order to study the characteristics and sedimentary environment of Chengqiangyan phosphate mine in Mianzhu City, the ore body was controlled by field geological survey, 14 trenching and tunnel engineering, and 226 ore samples were collected for relevant test and analysis.The results showed that the host strata of Chengqiangyan phosphate deposit are the first member of Shawozi Formation (D3s1) of Lower Devonian, and the ore body is basically consistent with the occurrence of stratum,which is layered and stratoid, with strike of 300°～357 ° and dip angle of 31°～56 °.The thickness of ore body is 1.06～13.86m, and the grade (P2O5) is 18.29%-35.57%. The grade is positively correlated with the thickness of phosphorous layer and ore body, that is a typical Shifang type phosphate mine.The lithofacies assemblage is "kaolinite claystone aluminophosphatite phosphorite".The natural type of the ore is clayey or sandy gravel Phosphorite Ore, and the industrial type is siliceous and silicate phosphorite ore.The contents of P2O5,Cao and I are stable; correlation and cluster analysis show that P2O5,Cao and F are closely related;Fe2O3 and A12O3,MgO and CO2 are closely related; Fe2O3, A12O3 and RE2O3 are obviously related. The characteristic values of trace elements indicate that the wall rock phosphorite was formed in the dry and oxygen rich marginal marine environment. Based on the analysis of regional metallogenic geological conditions, it is considered that the phosphate ore is mainly formed by weathering leaching sedimentation and later by chemical sedimentation in the coastal shallow sea.The prospecting criteria are as follows:Sinian Dengying Formation"flower spot" dolomite, Devonian Shawozi formation dolomite→paleokarst erosion surface,phos-phorous dolomite, phosphorous clay rock→siliceous phosphorite, clayey phosphorite,breccia phosphorite.