Abstract: This is an article in the field of ceramics and composites. In order to study the adsorption effect of modified bentonite on heavy metal ions in sewage, the effects of pH value, initial concentration, time, solid-liquid ratio, temperature and particle size on the adsorption effect of bentonite were analyzed. And microscopic means were used to study the changes of the internal mineral composition of the bentonite before and after the adsorption of heavy metal ions and the change law of the infrared spectra. The results showed that when the modified bentonite content was 0.2 g, the adsorption time was 1.5 h, the temperature was set to 40 ℃, the pH value was set to 6, the initial concentration was set to 200 mg/L and the solid-to-liquid ratio was set to 0.8 g/L, the adsorption effect was the best. After the modified bentonite had undergone an adsorption test, an obvious CuSO₄ diffraction peak could be detected. However, other mineral components inside the modified bentonite remained unchanged, which also showed that the modified bentonite could effectively adsorb copper ions in sewage.