Taking into account the characteristics of hydrogeological and hydrologic logging work, the author has examined the commonlyused equations for calculating mineralization intensity or resistivity of strata water by means of self-potential curves, and then put forward his own calculating method and formula suitable for high-requirement hydrogeological logging work. It is considened that, of quite a few factors affecting diffusion-adsorption coefficient k_t, the variation in chemical composition and combination ratio of the solutions seems to be most important. Through statistical analysis, parameters of a, b, and k, for mixed solutions with different saline compositions are obtained, the physical implications of these parameters are clarified, and the reasonable acquisition of numerical values in practical work is discussed. Finally, the effectiveness of this me-thod is illustrated with the help of practical data and^comparison by diagrams. This also leads to an extension of its application scope.