The present invention discloses a novel magnetic ferric oxide hollow microsphere contrast agent. According to the present invention, the microsphere has a hollow inorganic/organic/inorganic three-layer structure, the cavity is positioned in the center of the microsphere, air is filled in the internal, the outer layer of the cavity is alpha-Fe2O3 magnetic particles, the middle layer is core/shell polymer nanometer microspheres obtained by carrying out free radical copolymerization on a polyacrylonitrile-polyacrylic acid random copolymer, polyacrylic acid and divinylbenzene, the carboxyl on the inner surface and the iron salt can form the coordination bond or ion bond so as to provide the stability between the copolymer and the alpha-Fe2O3 magnetic particles in the inner layer, the outer layer is silicon dioxide, and the carboxyl on the microsphere surface and the silanol on the silicon dioxide surface produce the hydrogen bond effect so as to connect; and the magnetic ferric oxide composite medical contrast agent has the following advantages that: the polymer microspheres belong to the nanoscale particles, the contrast agent can provide the targeting positioning function with the alpha-Fe2O3 magnetic particles in the inner layer, the silicon dioxide hollow microsphere has good biocompatibility and good mechanical stability, and the internal cavity can produce the strong echo signal under the contrasting mode.