A modified polyacrylamide gel route with urea used as fuel was used to synthesize the MFe2O4 (M = Mg, Ca, Ba) iron oxides with high adsorption capacity for removal of Cd(II) from water treatment. The phase structure, functional group, porous structure and adsorption performance of MFe2O4 (M = Mg, Ca, Ba) iron oxides were characterized by X-ray-diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), N-2 adsorption-desorption isotherm and 721 spectrophotometer. The result indicates that the phase forming temperature of MFe2O4, the content of carbonate ion in MFe2O4 increases with the increasing of the radius of M-site metal ion. The E-g value, BET surface area and adsorption capacity for removal of Cd(II) from water treatment decreases with the increasing of the radius of M-site metal ion. The experimental isotherm of MFe2O4 (M = Mg, Ca, Ba) iron oxides were described by the Langmuir model. MgFe2O4 iron oxide exhibits a best adsorption performance for removal of Cd(II) from water treatment by the adsorption process, with a maximum adsorption capacity of ca. 221.36 mg/g than that of other iron oxides. The present synthetic route could be possibly extended to synthesize other porous metal oxide materials with special porous structures for various applications.