Core−shell poly (acrylamide) modified magnetic nanogels with narrow particle size distribution were synthesized in aqueous solution with surfactant free ,via, photochemical method. The size of the nanogels can be controlled by varying the reaction time, or the concentrations of monomer and cross−linker. After Hoffmann degradation of amido groups, the magnetic nanogels with amino groups were also obtained. The magnetic nanogels were characterized by Fourier transform infrared spectroscopy (FTIR), photo correlation spectroscopy (PCS), atomic force microscopy (AFM) and transmission electron microscopy (TEM), respectively.