Industrial production brings serious Cr(Ⅵ) pollution problems, so as to explore new treatment methods for Cr(Ⅵ), In this paper, modified montmorillonite was prepared by modifying montmorillonite with starch and lanthanum nitrate, and its adsorption mechanism and effect on Cr(Ⅵ) were explored. The modified mechanism and modified monundonerization properties were characterized by Zeta potential, X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR), and scanning electron microscopy analysis(SEM). The results showed that: Lanthanum-modified montmorillonite and starch-modified lanthanum-modified montmorillonite have better adsorption effects on 10 mg/L Cr(VI) polluted solution, which are 73.9% and 58.6%, respectively, while Na-based montmorillonite Cr(VI) has no adsorption capacity. Both lanthanum and starch only exist on the surface of montmorillonite, which can reduce the overall electronegativity of montmorillonite, so that montmorillonite has the ability to adsorb Cr(VI), At the same time, after the surface of montmorillonite modified by lanthanum nitrate is covered with hydroxyl groups, it is easy to form surface coordination complexes with anions, which further enhances its adsorption effect, and provides a new research idea and direction for the adsorption and removal of Cr(VI).