OBJECTIVE： To prepare Magnetic graphene oxide modified by folic acid （FA-GO-Fe3O4）， and to characterize it and study its magnetism. METHODS： Using graphene oxide （GO）， ferric chloride hexahydrate and ferrous chloride tetrahydrate as raw material， magnetic graphene oxide （GO-Fe3O4） was synthesized by hydrothermal coprecipitation method. FA-GO-Fe3O4 was obtained by linking amido bond to folic acid. GO， GO-Fe3O4 and FA-GO-Fe3O4 were characterized by scanning electron microscopy， infrared spectroscopy， X-ray diffraction （XRD） and particle size and Zeta potential analyzer respectively. Zeta potential was measured. The magnetism of FA-GO-Fe3O4 were investigated by the action of external magnetic field and hysteresis loop. RESULTS： Compared with GO and GO-Fe3O4， scanning electron microscopy and XRD showed that the structure of GO destroyed in the synthesis of FA-GO-Fe3O4， and there were particles attached on the surface， and amorphous phase peaks between 15 ° and 30 °. Infrared spectroscopy showed that FA-GO-Fe3O4 had absorption peaks at 574 cm－1 and 1 640 cm－1， which belonged to the characteristic absorption of Fe-O and —CONH— respectively. Zeta potentials of GO， GO-Fe3O4 and FA-GO-Fe3O4 were －24， 5.62 and －22.7 mV， respectively. FA-GO-Fe3O4 had obvious magnetism under external magnetic field， and its saturation magnetization was about 20-25 emu/g under room temperature and applied positive and negative magnetic fields. CONCLUSIONS： FA-GO-Fe3O4 prepared in this study has superparamagnetism and is more stable than GO-Fe3O4.