In this work, pure gadolinium oxide (Gd2O3) and mixed gadolinium oxide (Gd2O3) - magnesium oxide (MgO) composites were synthesized by simple hydrothermal method and calcination treatment. Two kinds of materials were used to remove uranyl ions from aqueous solution and characterized the structure and morphology by means of XRD, FT - IR, SEM, EDS and XPS. MgO was introduced into Gd2O3 material, which effectively avoided the agglomeration of Gd2O3 material and increased the adsorption capacity.The effects of different initial pH, initial uranium concentration and contact time on the adsorption performance of UO22+ were investigated by static adsorption experiments. The thermodynamic fitting of Langmuir and Frenudlich equations showed that the adsorption process of the two kinds of materials were more consistent with the Langmuir equation. At 25℃, the maximum adsorption capacities of Gd2O3 and Gd2O3-MgO for UO22+ were 473.43 mg·g-1 and 812.41 mg·g-1, respectively. Thermodynamic parameters (△G0<0, △S0>, and H0<0) indicated that the adsorption properties are exothermic and spontaneous. The possible adsorption mechanism is derived from XPS and FT-IR analysis, which mainly involves the complexation of -OH and U(Ⅵ) generated by the hydration on the surface of the materials.