Metallogenic efficiency (ME), is the ratio of reserves of a metal to its total amount in both the deposits and alteration zones. We present a new method for calculating ME on a regional scale, based on stream sediment geochemical anomalies. Given a study area, the MEs of ore-forming elements should be weighted by their concentration factors, in order to quantitatively assess the potential of these elements for generating economic deposits. Taking Shizhuyuan ore-field as a case study, ore-forming elements with greater MEs exhibit greater ore-generating potentials. Accordingly, regions with geochemical anomalies of several elements with high-ranking WMEs (weighted metallogenic efficiencies) are favorable sites for exploration of polymetallic deposits. Moreover, in terms of elements such as W or Sn, the WME in the Shizhuyuan ore-field was greater than in the Wangxianling ore-field, consistent with the greater tonnage of mineral reserves in the former. Given a certain ore-forming element, therefore, its ore-generating potentials in different regions are quantitatively comparable to its WMEs. In summary, WME is an important parameter for quantitative evaluation of resource potentiality and resource prospection.