The modified activated carbon material (Mg-GAC) was prepared by reactive crystallization technique. The microstructure of the activated carbon before and after modification was analyzed by SEM and XRD. The adsorption time, pH value and temperature of GAC and Mg-GAC were studied. The effect of adsorption of copper ions in wastewater. The results show that the modified GAC greatly increases its specific surface area and increases to 738.01m2/g. When the dosage of Mg-GAC was 0.3g, the concentration of copper ion was 40mg/L, the temperature was 25 ℃, and the pH was 7 for 2 h, the adsorption amount reached 11.66mg/g. In addition, the adsorption process of copper ions conforms to the Langmuir isotherm model.