In this paper, the magnetic microcapsules were prepared by means of solvent evaporation. Core material was magnetofluid whose nano OA-Fe3O4 (oleic acid modified Fe3O4) magnetic particles prepared with coprecipitation were dispersed in different solvent media. Shell material was PMMA (polymethyl methacrylate). Optimum core material and emulsifier were selected. The encapsulation parameters, including mass fraction of emulsifier, core material to shell material mass ratio and shearing emulsification rate were investigated respectively. The active ingredient, morphology, thermal property and magnetic responsiveness of OA-Fe3O4 and magnetic microcapsule were characterized by XRD, FTIR, TEM, SEM, optical microscope and VSM (vibrating sample magnetometer). The results show that the effective ingredient of nanoparticle prepared by coprecipitation is Fe3O4, which can be successfully microencapsulated. The OA-Fe3O4 exhibits monodispersity, and its particle size is 3-15nm. OA-Fe3O4 also shows superparamagnetism, and its saturation magnetization is 43.3emu/g. The optimum process parameters of preparing magnetic microcapsules as follows: Magnetofluid of OA-Fe3O4 dispersing in n-C16H34 is core material, mass fraction of emulsifier SDS (sodium dodecyl sulfonate) to total emulsion is 2%, core material to wall material mass ratio is 5:1, and shearing rate is 800r/min. The wall thickness of magnetic microcapsule is 1-2μm and the particle size is concentrated on 10±2μm. The saturation magnetization of magnetic microcapsule is 43.3emu/g, which shows good magnetism response under magnetic field.