The　folic　acid　(FA)-conjugated　Fe3O4　magnetic　nanoparticles　(MNPs)　were　synthesized　by　co-precipitation　of　Fe3+　and　Fe2+　solution　followed　by　surface　modification　with　carboxymethyl　dextran　(CMD)　to　form　carboxymethyl　group　terminated　MNPs,　then　FA　was　conjugated　with　the　carboxyl　group　functionalized　MNPs.　The　morphology　and　properties　of　obtained　nanoparticles　were　characterized　by　X-ray　powder　diffraction　(XRD),　Fourier　transform　infrared　spectroscopy　(FT-IR),　UV-visible　spectra　(UV-vis),　transmission　electron　microscopy　(TEM),　dynamic　light　scattering　(DLS),　vibrating　sample　magnetometer　(VSM)　and　thermogravimetric　analysis　(TGA).　The　FA-conjugated　MNPs　exhibited　relatively　high　saturation　magnetization　and　fast　magneto-temperature　response　which　could　be　applied　to　hyperthermia　therapy.　To　determine　the　accurate　targeting　effect　of　FA,　we　chose　FA-conjugated　MNPs　as　MRI　contrast　enhancement　agent　for　detection　of　KB　cells　with　folate　receptor　over-expression　in　vitro　and　in　vivo.　The　results　show　that　these　magnetic　nanoparticles　appear　to　be　the　promising　materials　for　local　hyperthermia　and　MRI.　©　2014　Published　by　Elsevier　B.V.