The association and content of minerals in 51 soil samples from Chongqing segment of the Three Gorges Reservoir were investigated by XRD. The results indicate that quartz, plagioclase and K-feldspar comprise main mineral species in the soils, and quartz content is high in most samples. Clay minerals in the samples are composed mainly of illite and montmorillonite, together with minor other minerals. By reference to the surface water body quality standard, the authors calculated the thresholds of pollution of heavy metals CA, lag, Pb, Cu in the soils using the formula of critical adsorption capability of metal ions adsorbed on soil minerals, and evaluated the pollution situation of these soils. The results show that the contents of contaminative elements in the soils are inconsistent with their assessment values of ecologic effect. The contents of CA and Fig in the soils fail to reach the critical values of pollution, and the risk of geochemical time bomb for the two harmful elements should not be neglected in the area. There exists serious pollution of Pb and Cu in the studied soils as well as in their parent rocks, which probably reflects the high geochemical background of the two elements in this area.