Magnetic Fe3O4-poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol) (PZS) hybrid hollow microspheres, in which Fe3O4 nanoparticles were firmly incorporated in the cross-linked PZS shell, have been fabricated through the formation of core/shell PS/Fe3O4-PZS composites based on template-induced covalent assembly method, followed by core removal in a tetrahydrofuran solution. The morphology, composition, thermal property, and magnetic property of the magnetic hollow microspheres were characterized by scanning electron microscope, transmission electron microscope, Fourier transform infrared spectra, energy dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetric analysis, and vibrating sample magnetometer respectively. Results indicated that the typical hollow microspheres had about 950 nm of inner diameter and about 210 nm of shell thickness, 440 degrees C of initial decomposition temperature under nitrogen atmosphere, and 13.3 emu g(-1) of magnetization saturation. Furthermore, the shell thickness of magnetic hollow microspheres could be easily controlled by tuning the mass ratio of PS to comonomers. As-fabricated hybrid hollow microspheres exhibit great potential as good catalyst supports.