Abstract: Dayishan granite is controlled by the Dayishan NW-trending tenso-shear fault structure, with the multiple intrusion characteristics, and the main mineral deposits related to the granite are tin-polymetallic deposits. There are three types of tin deposits in this prospecting area, i.e., altered greisen vein type, granite type and skarn type. The greisen veins of Baishaziling ore block in the planar alignments exhibit oval distribution on a flat, and the length, thickness and quality of veins taper from the middle part outwards, and so does the single vein. The veins at both ends of roof and floor present opposite scratches, and hence it is concluded that there is an oval concealed mother rock body, with its top forming the granite type. For this study the authors conducted tunnel deep drilling, with rich tin orebody of granite type seen in the upper part, and tungsten orebody seen in the lower part. The authors predict that the deep ore exploration has good prospect.