Polyacrylamide-coated magnetic nanogels were synthesized via photochemical method in surfactants and initiators free aqueous system at room temperature. After Hoffmann elimination of carbonyl and further modification with methoxy poly(ethylene glycol) (MPEG), the MPEG-modified superparamagnetic nanogels (MSN) with better hydrophilicity and biocompatibility were obtained. The MSN were characterized by FTIR, XRD, SEM and PCS. Covalently linked with (188)Re complex, the (188)Re-labeled MSN were prepared and intravenously injected into the left ears of the anesthetized rabbits in control group (without external magnetic field) or in targeting group (in presence of external magnetic field). The average radioactivity distribution of organs in control group was detected and the magnetic targeting feature was investigated in targeting group.