Systematic sampling and processing of such bentonite deposits as Erdaohe, Hartao, Beiwopeng and Xiazhalanboluo deposits in Zidutai-Yusi Basin were carried out, and petrological and mineralogical characteristics of ore-bearing rock series related to the deposit were investigated. The samples were analyzed and tested by means of basic analysis, XRD, chemical analysis and cation exchange capacity. The results show that rocks rich in volcanic glass, such as sedimentary tuff, rhyolitic ignimbrite and sandy tuff, are easier to hydrolyze to form bentonite ore. Bentonite is generally alkaline, and its mineral composition is mainly montmorillonite, followed by associated minerals such as quartz and plagioclase. XRD and cation exchange capacity show that calcium-based bentonite and sodium-based bentonite are developed in Erdaohe and Hartao bentonite deposits on the north side, showing layered characteristics of upper calcium-based bentonite and lower sodium-based bentonite. The results obtained by the authors are of guiding significance in search for sodium bentonite deposits in the deep part of Xiazhalanboluo and Beiwopeng bentonite deposits in the south of the basin.