Abstract: In this paper, the energy spectrum analysis of clay minerals in the middle and lower reaches of Weihe River in Shaanxi Province has been carried out by using 7 kinds of oxide data from the investigation of land quality geochemistry. And then, a set of quality conservation equations has been established, which transformed the problem of solving clay mineral content into solving the optimal solution of linear programming to study the distribution of clay minerals. The results show that this method is simple and accurate. Soil development is still at a relatively early stage. The main viscous minerals are illite, montmorillonite, kaolinite, while the secondary clay minerals are vermiculite and chlorite. The different type of landform cause the difference in clay mineral content, reflecting the different weathering processes. For example, the Weibei platform is dominated by biotite, chlorite and vermiculite. The middle and low mountainous areas are dominated by feldspar, mica, illite, montmorillonite and kaolin. The northern margin of the Qinling Mountains is composed of two weathering processes, while the valley area is weak in both weathering processes. In addition, the distribution characteristics of clay minerals also reflect the soil type and its nature, indicating the alternating changes of cold dry and warm ancient climate in different geological times.