A magnetic nanomedicine for tumor suppression and therapy, comprising: a core, made of magnetic nanoparticles; a shell, encapsulating said core and is made of carboxylated polyaniline (SPAnH); and a tumor suppression medicine Epirubicin (EPI) or Doxorubicin (DOX) covalently bonded onto said shell. Said magnetic nanomedicine is capable of improving its thermal stability, and it can be dissolved uniformly in water, plus its superparamagnetic property, thus it can be guided by an outside magnetic field to concentrate to the site of tumor distribution to increase the local medicine concentration and enhance therapy effect.