Provided are a modified Na-montmorillonite and a preparation method thereof, wherein the content of Na+ in the modified sodium-montmorillonite, calculated as Na2O, is not less than 2.0%. The modified Na-montmorillonite has more reasonable microstructure, higher performance, and better quality. Also provided are a method for preparing a modified nanometered Na-montmorillonite from the modified Na-montmorillonite, and the modified nanometered Na-montmorillonite obtained by the method. Also provided are uses and a pharmaceutical composition of the modified Na-montmorillonite or modified nanometered Na-montmorillonite. Figure 1 is the representative figure.
