The application of constant element geochemical characteristics to the evaluation of ore-bearing properties has important significance. In this paper, the authors found that there is a clear boundary value of the aluminum saturation index between the orebody and the barren body among the 210 intermediate-acid rock bodies in Shanxi Province. Aluminum saturation may be an important indicator to reflect the capability of the intermediate-acid magma for releasing the ore-forming elements. The result obtained by the author is of reference value for evaluating ore-bearing potential of intermediate-acid magma in other areas.