Montmorillonite is a large surface area and wide distribution clay mineral, it is also one of main activated components in soil. The montmorillonite interlayer is a special site in chemical reaction. In this paper we review the reaction mechanisms of inorganic cations, organic cations and herbicide molecules adsorbed, de-adsorbed, oxidized-reduced and catalyzed-degraded on montmorillonite interlayer. We also discuss the effect and significance to environment of their environmental chemistry behaviors.Montmorillonite can adsorb the poisonous heavy metal element and organic pollutants, and the interlayer is a good detained site for those environmental pollutants. So the research on the interlayer of montmorillonite can understand the reason that environmental pollutants migrate, precipitate, and degrade in environment. And it will provide the theoretic foundation to control environmental pollution better.