Abstract: The deep prospecting of the Linglong gold deposit is always a difficult point in the scientific research and production of the deposit. In this paper, through the observation of geological characteristics of No. 50 vein and the sampling of cross vein and following-vein in different middle sections and with the undisturbed rock mass as the background sample, the authors determined the major elements and 14 trace elements. The geochemical characteristics of the orebody and surrounding rocks on both sides were compared by taking the ore-passing section as the unit, the correlation and cluster analysis of elements were conducted, and different altered rock masses and orebodies were counted. According to the average and standard values of trace elements, the geochemical primary halo method was used to map the primary halo on the plane and along the longitudinal section, and the metallogenic prognosis of No. 50 vein was carried out by using the geochemical method of three-dimensional structural altered rocks. The results are as follows: ①As, Ag, Bi, Co, Mo are the best indicator elements for Au in vein No. 50; ②The values of Au, Ag, As, Cu, Pb, Bi and Mo obviously increase from surrounding rocks to the orebody; ③The vertical zonation sequence of primary halo of No.50 vein is Mn→Mo→As→V→Bi→Co→Au →Ni→Cu→Ag→Pb→Sb→Zn from top to bottom, showing "reverse zonation" sequence. Based on the above research results and geological analysis, it is predicted that No. 50 vein body has a good metallogenic prospect in the deep part.