【Objective】 Bentonite, as is widely used in industry and agriculture, has become an research hotspot in material science agricultural science and environmental science. Montmorillonite is the main mineral component of bentonite, and its content and unique mineralogical properties determine the economic and application values of bentonite. Bentonite ore is found widely distributed in Jiangsu Province. From the perspective of the current development and utilization of bentonite in China, the mineral is mined at a local small-scale to make low-level processing products. It is necessary to study how to further exploit the mineral resource. In this paper, based on the researches reported, the bentonites in South Jiangsu were chosen for analysis of their mineralogical properties, in an attempt to provide certain scientific basis for further development and reasonable utilization of the mineral. 【Method】To comprehensively explore mineralogical properties of the mineral, bentonite samples were collected from eight major bentonite mines in South Jiangsu and analyzed for pH, mineral composition, chemical composition, particle size distribution, cation exchange capacity and cation composition. 【Result】Results show that the natural bentonites in South Jiangsu tend to be high in pH, with an average being about 8.83 and are mainly composed of montmorillonite and a certain amount of associated minerals, which vary in type and content with origin of the samples. X-ray deflection analysis shows that the 8 samples are all calcium-based bentonites. Their chemical composition and cation composition varies somewhat in line with their metallogenic environments. Generally their CECs tend to be low. In the samples, CEC is found to be closely and positively related to the content of montmorillonite. All the findings in this study on physicochemical and mineralogical properties of the bentonite in South Jiangsu demonstrate that it has a good prospect in exploiting the resource.【Conclusion】The natural bentonites in South Jiangsu are all of the calcium-based type, and composed mainly of montmorillonite and certain associated minerals, which vary slightly with the origin of the samples. The samples also vary slightly in chemical composition due to their difference in metallogenic environment. The samples are generally basic in pH, which is mainly attributed to derivation of the mineral from its parent rock under an alkaline environment. The natural bentonite in South Jiangsu is generally low in cation exchange capacity, which is related to the content of montmorillonite in bentonite. The relationship is positive and significant. The content of montmorillonite decreases with increasing particle size, and montmorillonite exists mainly in particles <50 μm in size.