In this paper, magnetic polymer microspheres were prepared via emulsion-solvent evaporation method, with magnetic Fe3O4 nanoparticles and biodegradable polymer poly(lactic-co-glycolic acid). The structures and properties of microspheres were characterized with Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy and vibrating sample magnetometer, and the electromagnetic induction heating property was also investigated. The obtained two magnetic polymer microspheres with Fe3O4 content of 10.1% and 18.8% exhibited saturation magnetization values of 2.3 emu/g and 6.8 emu/g, and temperature increased 9℃ and 16.5℃ under the electromagnetic induction. Results suggest that the obtained magnetic polymer microspheres meet the heating requirement of hyperthermia and have potential applications in magnetic hyperthermia or thermochemotherapy of cancer.