The composition of clay minerals and the contents of K-bearing minerals and slowly available Potassium of nine samples were determined by chemieal and X-ray diffraction methods The resuits showed that the clay minerals Present in the clay fraction (<2μ) of all these samples were hydromioa,ehlorite,kaolinite and montmorillonite etc.The eontent of K-bearing minerals was very high(35%) in the soil derived from the Pruplish sliale,and followed by that in the soil derived from lacustrine deposits (25%),while those in the other soils ranged only from 14-19%.