The K9 vein is one of the main veins of the Longmendian Silver Deposit.The structural primary halo method is applied to make deep ore body prediction.The result shows that the ore-forming process has the characteristics of multi-stage superposition,and the ore body on 840 m elevation exhibits an superposition of frontal halo indicator elements; Axial zoning sequence of the indicator elements downwards on the ore veins by calculation is described as follows:W-Au-As-Pb-Hg-Mo-Zn-Bi-Ag-Sb-Cu,assuming frontal halo and tail halo coexisting phenomena and reverse zoning characteristics.According to the structural primary halo characteristics of K9 ore vein,the ore vein structural primary halo model is constructed and it is predicted that below the 840 m elevation there are blind ore bodies and great prospecting potentials.