In order to achieve a targeting drug carrier system, magnetic polylactic acid (PLA) microspheres were synthesized by modified Fe3O4 and compound emulsifiers with the method of emulsion solvent evaporation. The morphology, size, and size distribution of magnetic microspheres were measured by scanning electron microscopy and laser particle size analyzer, respectively. The result indicated that modified Fe3O4 and compound emulsifiers were necessary for fabrication of magnetic PLA/Fe3O4 microspheres. By analyzing the Fourier transform infrared spectra, it was found that all of existing functional groups of PLA and Fe3O4 were kept invariable. Besides, magnetic property of microspheres was measured by vibrating sample magnetometer, and related results showed that the magnetic microspheres were super paramagnetic and the magnetization can be reached to 12.6emu/g. On the basis of the thermalgravimetric analysis, the research found that magnetic Fe3O4 was loaded into the PLA microspheres whose content of magnetic particles was 15wt%.