Abstract: This is an article in the field of environmental engineering. In order to study the effect of kaolin on the adsorption performance of wastewater containing Cu²⁺ and Pb²⁺, experiments on the adsorption of heavy metal ions by kaolin under different initial concentrations, temperatures, adsorption time, kaolin content and pH values are carried out. And analyzed the results of Cu²⁺ and Pb²⁺ co-adsorption test by kaolin. The results show that the adsorption effect of kaolin on metal Pb²⁺ ions is better than the adsorption effect of kaolin on metal Cu²⁺ ions. Combining the test results and economic benefits, when the initial concentration is 200 mg/L, the pH is 6, the temperature is 30 °C, the kaolin content is 1.5 g, and the adsorption time is 2.0 h, Kaolin has the best adsorption effect on metal Pb²⁺ and Cu²⁺ ions. The adsorption capacity of metal Pb²⁺ ions reached 56.38, 56.22, 58.76, 35.75, and 42.42 mg/g, respectively. The adsorption capacity of metallic Cu²⁺ ions is 45.99, 47.45, 47.27, 25.26, 22.52 mg/g. On the whole, the adsorption capacity of kaolin for co-adsorbed metal ions (Cu²⁺, Pb²⁺) is smaller than that of a single ion. This is because two metal ions will affect each other's adsorption process during the adsorption process. The fit of Langmuir model to the test curve is much higher than the fit of Freundlich model to the test curve. This shows that the Langmuir isotherm adsorption model is more suitable for the change law of the amount of metal ions adsorbed by kaolin. Furthermore, it is proved that the adsorption of heavy metal ions by kaolin belongs to surface adsorption, and the adsorbed heavy metal ions exist independently of each other.