Magnetic polymer-coated microspheres were prepared by the microemulsion polymerization and the Fe3O4/CdSe/ZnS magnetic fluorescent bifunctional nanocomposites were obtained by depositing heterogeneous semiconductor on magnetic nanoparticles. They were investigated by TEM, TGA, optical microscopy and VSM (vibrating sample magnetometer). The results indicate that the magnetic microspheres were superparamagnetic, well shaped spheres, mono-dispersed and good thermal stability. The Fe3O4/CdSe/ZnS nanocomposites are also superparamagnetic ,and are about 8 nm in size. The quantum yield of the nanocomposites increaces due to passivation of the surface of the magnetic-CdSe nanocomposites with a ZnS layer.