Abstract: This study investigated the clay mineral composition of the soil profiles of cropland for soybean/maize rotation, forest land, grassland, and farmland returned to forest in the black soil regions of the northern Songnen Plain through field investigation, the analysis of soil chemical composition, the X-ray diffraction (XRD) spectrum analysis of soil clay minerals, and the analysis of soil weathering degree. The purpose of this study is to explore the chemical composition, clay mineral composition, and weathering change patterns of the soil profiles of the land for different uses and their environmental implications. The results show that in the soil profiles, the land for different uses is in the order of grassland > cropland > forest land > wasteland regarding the potassium, sodium, and calcium contents, in the order of cropland > forest land > grassland > wasteland regarding the organic carbon content in the soil at a depth less than 60 cm, in the order of wasteland > grassland > forest land > cropland regarding the organic carbon content in the soil at a depth greater than 60~80 cm, in the order of farmland returned to forest and wasteland > forest land > cropland > grassland regarding the soil weathering degree, and in the order of wasteland > grassland and forest land > cropland in terms of the soil leaching degree. The clay minerals in the soil of land for different uses area mainly consist of montmorillonites, kaolinites, vermiculites, hydromicas, and chlorites. The cropland, forest land, grassland, and wasteland are dominated by the 2:1 type of non-expansive clay minerals, the 2:1 type of non-expansive clay minerals, the 2:1 type of expansive clay minerals, and the 1:1 type of clay minerals, respectively. As shown by the comparison of the clay mineral assemblages and their contents in the soil of land for different uses in the study area, as well as the calculation of the weathering degree of the soil profiles, minerals such as chlorites in the soil transition to kaolinites and montmorillonites, hydromicas transition to vermiculites, and the environment has changed from a dry and cold climate to a wet and hot climate as the weathering degree and pedogenesis deepen.